Programming-with-Python_-II-munotes

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1 UNIT 1
1
PYTHON FILE INPUT - OUTPUT
Unit Structur e
1.1 Introduction
1.2 Opening files in python
1.3 Closing files in python
1.4 Write to an existing file
1.5 Create a new file
1.6 Python delete file
1.7 Python directory
1.7.1 Get current directory
1.7.2 Changing directory
1.7.3 List directories and files
1.7.4 Making a new directory
1.7.5 Removing directory or file

1.1 INTRODUCTION
Files are named locations on disk to store information. They are used to
permanently store data in a non -volatile memory e.g. hard disk.
Random Access Memory (RAM) is volatile memory means it loses its
data when the computer is turned off, we use files for future use of the
data by pe rmanently storing them.
When we want to read from or write to a file, we need to open it first.
When we have finished our work, it needs to be closed so that the
resources that are attached with the file are freed.
Hence, in Python, a file operation takes place in the following sequence:
1. Open a file
2. Read or write (perform operation)
3. Close the file
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Programming with Python – II
2 1.2 OPENING FILES IN PYTHON
Python has a built -in open() function to open a file.
The open() function returns a file object, which has a read() method for
reading the content of the file:
>>> f = open("test.txt") # open file in current directory
>>> f = o pen("C:/Python38/README.txt") # specifying full path
We can specify the mode while opening a ny file.
In mode, we specify whether we want to read r, write w or append a to
the file. We can also specify if we want to open the file in text mode or
binary mode.
 The default is reading in text mode. In this mode, we get strings
when reading from the file.
 On the other hand, binary mode returns bytes , and this is the mode to
be used when dealing with non -text files like images or executable
files.
Mode Description
r It opens a file for reading. ( By
default)
w It opens a file for writing. Creates a new file if it does
not exist or truncates the file if it exists.
x It opens a file for exclusive creation. If the file
already exists, the operation fails.
a It opens a file for appending at the end of the file
without truncating it. Creates a new file if it does not
exist.
t Opens in text mode. ( By default)
b Opens in binary mode
+ Opens a file for updating (reading and writing)
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Python File Input - Output

3 This is the test.txt file we have

Example 1.1

Output:

If the file is located in a different location, you will have to specify the file
path, as follows :
Example 1. 2

Output:

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Programming with Python – II
4  Read Only Parts of the File
By default the read() method returns the whole text, but you can also
specify how many characters you want to return:
Example 1. 3Return the 5 first characters of the file

Output:

 Read Lines
You can return one line by using the readline() method:
Example 1. 4Read one line of the file:

Output:

By calling readline() two times, you can read the two first lines:
Example 1.5 Read two lines of the file:

Output:
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Python File Input - Output

5 By looping through the lines of the file, we can read the whole file, line by
line:
Example 1.6 Loop through the file line by line


Output:

1.3 CLOSING FILES IN PYTHON
When we have completed performing operations on the file, we need to
properly close the file.
Closing a file will free up the resources that were attached with the file. It
is done using the close() method available in Python.
Python has a garbage collector to clean up unreferenced objects, but we
must not rely on it to close the file.
Example 1.7

Output:

Note:
You should always close your files, in some cases, due to buffering,
changes made to a file may not show until you close the file .


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Programming with Python – II
6 1.4 WRITE TO AN EXISTING FILE
To write to an existing file, we must add a parameter to
the open() function:
"a" - Append
It will append to the end of the file.
"w" - Write
It will overwrite any existing content.
Example 1.8
Open the file "test.txt" and append content to the file:

Output:

Example 1.9
Open the file "test.txt" and overwrite its content:

Output :
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Python File Input - Output

7 1.5 CREATE A NEW FILE
To create a new file in Python, use the open() method, with one of the
following parameters:
"x" - Create
It will create a file, returns an error if the file exist.
"a" - Append
It will create a file if the specified file does not exist.
"w" - Write
It will create a file if the specified file does not exist.
Example 1.10 Create a file called "myfile.txt"

Output:
Result: a new empty file is created!

Returns an error if the file exist

Example 1.1 1Create a new file if it does not exist:

Note: the "w" method will overwrite the entire file.
1.6 PYTHON DELETE FILE
To delete a file, we must import the OS module, and run
its os.remove() function . munotes.in

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Programming with Python – II
8 Example 1.1 2Remove the file "test.txt":

Note: test.txt got deleted from programs folder.
Check if File exist:
To avoid getting an error, you might want to check if the file exists before
you try to delete it:
Example 1.13 Check if file exists, then delete it:

Output:

Delete Folder
To delete an entire folder, use the os.rmdir() method:
Example 1.1 4Remove the folder "my programs ":

Output :

Note: You can only remove empty folders.
1.7 PYTHON DIRECTORY
If there are many files in our Python program, we can arrange our code
within different direct ories to make things more manageable.
A directory or folder is a collection of files and subdirectories. munotes.in

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Python File Input - Output

9 Python has the os module that provides us with many useful methods to
work with directories (and files as well).
1.7.1 GET CURRENT DIRECTORY
We can get the present working directory by using the getcwd() method of
the os module.
We use the OS module to interact with the operating system.
This method returns the current working directory in the form of a string.
Example 1.15

Output:

1.7.2 CHANGING DIRECTORY
In case if w e want to change the current working directory , we can do so
by using the chdir() method .
Syntax of chdir()
os.chdir(path)
Parameters:
path - The path to the new directory
The new path that we want to change into must be supplied as a string to
this method.
We can use both the forward -slash / or the backward -slash \ to separate the
path elements.
It is safer to use an escape sequence when using the backward slash.



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Programming with Python – II
10 Example 1.16

Output:

1.7.3 LIST DIRECTORIES AND F ILES
All files and sub -directories inside a directory can be listed using
the listdir() method.
This method takes in a path and returns a list of subdirectories and files in
that path.
If no path is specified, it returns the list of subdirectories and files from the
current working directory.
Example 1.1 7

Output:

1.7.4 MAKING A NEW DIRECTORY
We can make a new directory by usingmkdir() method.
This method takes in the path of the new directory.
If the full path is not specified, the new directory is created in the current
working directory.


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Python File Input - Output

11 Example 1.1 8

Result: a new folder is created!

1.7.5 REMOVING DIRECTORY OR FILE
A file can be removed (deleted) using the remove() method.
Similarly, the rmdir() method removes an empty directory.
Example 1.19

Output:

Note: The rmdir() method can only remove empty directories.
We can not remove a non -empty directory .



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Programming with Python – II
12 Example 1. 20

Output:

In order to remove a non -empty directory, we can use
the rmtree( ) method inside the shutil module.
Example 1. 21

Output:





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13 2
EXCEPTION HANDLING

Unit Structure
2.1 Introduction
2.1.1 Syntax error
2.1.2 Exceptions
2.1.3 Built -in Exceptions
2.2 Catching Exceptions
2.3 Catching Specific Exception
2.1 INTRODUCTION
Error in Python can be of two types i.e. Syntax errors and Exceptions .
Errors are the problems in a program due to which the program will stop
the execution.
2.1.1 Syntax Error
This error is caused bywrong syntax in the code. It leads to the
termination of the program.
Example 2.1





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Programming with Python – II
14 Output:

2.1.2 Exceptions
Exceptions are raised when the program is syntactically correct, but the
code resulted in an error. This error does not stop the execution of the
program; however, it changes th e normal flow of the program.
Example 2.2

Output:

Here, we are trying to divide a number by 0 hence it raised
ZeroDivisionError Exception.
Python hasbuilt -in exceptions that are raised when your program
encounters an errori.esomething in the program goes wrong.
When these exceptions occur, the Python interpreter stops the current flow
and passes it to the calling process until it is handled. If not handled, the
program may crash. munotes.in

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Exception Handling

15 For example:
Let us consider a program where we have a function A that calls
function B, which in turn calls function C.If an exception occurs in
function C but is not handled in C, an exception passes to B and then to A.
If it is never handled, an error message is displayed, and program comes to
a sudden unexpected halt.
Note: Exception is the base class for all the exceptions in Python.
2.1.3 BUILT -IN EXCEPTIONS
The table below shows built -in exceptions that are usually raised in
Python:
Exception Description
ArithmeticError Raised when an error occurs in numeric
calculations.
AssertionError Raised when an assert statement fails.
AttributeError Raised when attribute reference or
assignment fails.
Exception Base class for all exceptions.
EOFError Raised when the input() method hits an "end
of file" condition (EOF).
FloatingPointError Raised when a floating point calculation
fails.
GeneratorExit Raised when a generator is closed (with the
close() method).
ImportError Raised when an imported module does not
exist.
IndentationError Raised when indendation is not correct.
IndexError Raised when an index of a sequence does not
exist.
KeyError Raised when a key does not exist in a
dictionary.
KeyboardInterrupt Raised when the user presses Ctrl+c, Ctrl+z
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Programming with Python – II
16 LookupError Raised when errors raised cant be found.
MemoryError Raised when a program runs out of memory.
NameError Raised when a variable does not exist.
NotImplementedError Raised when an abstract method requires an
inherited class to override the me thod.
OSError Raised when a system related operation
causes an error.
OverflowError Raised when the result of a numeric
calculation is too large.
ReferenceError Raised when a weak reference object does
not exist.
RuntimeError Raised when an error occurs that do not
belong to any specific expections.
StopIteration Raised when the next() method of an iterator
has no further values.
SyntaxError Raised when a syntax error occurs.
TabError Raised when indentation consists of tabs or
spaces.
SystemError Raised when a system error occurs.
SystemExit Raised when the sys.exit() function is called.
TypeError Raised when two different types are
combined.
UnboundLocalError Raised when a local variable is referenced
before assignment.
UnicodeError Raised when a unicode problem occurs.
UnicodeEncodeError Raised when a unicode encoding problem
occurs.
UnicodeDecodeError Raised when a unicode decoding problem
occurs.
UnicodeTranslateError Raised when a unicode translation problem
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Exception Handling

17 ValueError Raised when there is a wrong value in a
specified data type.
ZeroDivisionError Raised when the second operator in a
division is zero.

2.2 CATCHING EXCEPTIONS
Try and Except Statement
Try and except statements are used to catch and handle exceptions in
Python. Statements that may raise exceptions are kept inside the try
clause and the statements that handle the exception are written inside
except clause.
Example:
Let u s try to access the array element which doesn’t exist i.e whose index
is out of bound and handle the corresponding exception.
Example2.3

Output:

In the above example,statements that may cause the error are placed
inside the try statement (second print statement in our case).
The second print statement tries to access the fifth element; which is not
there in the list;so it throws an exception. This exception is then caught
by th e except statement.
2.3 CATCHING SPECIFIC EXCEPTION
A try statement can have more than one except clause, to specify
handlers for different exceptions. Please note that at most one handler
will be executed. munotes.in

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Programming with Python – II
18 For example, we can add IndexError in the above code.
The general syntax for adding specific exceptions are –
try:
# statement(s)
except IndexError:
# statement(s)
except ValueError:
# statement(s)
Example2.3 Catching specific exception in Python

Here fun(5) is commented.
Output:

If you comment the line fun(3), the output will be : munotes.in

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Exception Handling

19

Here fun(3) is commented.
Output:

In the above example, python tries to access the value of b, so
NameError occurs.
 TRY WITH ELSE CLAUSE
In python, you can also use the else clause on the try-except block
which must be present after all the except clauses. The code will
enter else block only if the try clause does not raise an exception.
Example 2.4 Try with else clause


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Programming with Python – II
20 Output:

 FINALLY KEYWORD IN PYTHON
Python provides a keyword finally , which is always executed after the
try and except blocks. The finally block always executes after normal
termination of try block or after try block terminates due to some
exception.
Syntax:
try:
# Some Code....
except:
# optional block
# Handling of exception (if required)
else:
# execute if no exception
finally:
# Some code .....(always executed)
Example 2.5 finally keyword in python

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Exception Handling

21 Output:

Example 2.6

Output:

RAISING EXCEPTION
The raise statement allows the programmer to force a specific exception
to occur.This must be either an exception instance or an exception class
(a class that derives from Exception).
Example 2.8

The output of the above code is simply “ An exception” but a Runtime
error will also occur at the end due to raise statement in the last line. So,
the output on your command line will look like this:



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Programming with Python – II
22 Output:

Example 2.9
Raise an error and stop the program if value of x is lower than 0

Output:

The raise keyword is used to raise an exception.
You can define what kind of error to raise, and the text to print to the user.
Example 2.10 Raise a TypeError if x is not an integer

Output:


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23 3
REGULAR EXPRESSIONS
Unit Structure
3.1 Introduction
3.2 Reg Ex functions
3.3 Metacharacters
3.4 Special sequences
3.5 Sets
3.1 INTRODUCTION
Regular Expression, or aRegEx, is a sequence of characters that forms a
search pattern.
RegEx can be used to check if a string contains the specified search
pattern.
 Reg Ex Module
Python has a built -in package called re, which can be used to work with
Regular Expressions.
Import the re modu le:
Import re
 Reg Ex in Python
Once you have imported re module, you can start using regular
expressions:
Example 3.1 Search the string to see if it starts with "The" and ends with
"Spain":
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24 Output:

3.2 REGEXFUNCTIONS
The re module offers a set of functions that allows us to search a string for
a match.
Function Description
Findall Returns a list containing all matches.
Search Returns a Match object if there is a match anywhere in the
string.
Split Returns a list where the string has been split at each match.
Sub Replaces one or many matches with a string.

3.3 METACHARACTERS
Meta characters are characters with a special meaning.
Character Description Example
[] A set of characters "[a-m]"
Signals a special sequence (can also be used to
escape special characters) "\d"
. Any character (except newline character) "he..o"
^ Starts with "^hello"
$ Ends with "world$"
* Zero or more occurrences "aix*"
+ One or more occurrences "aix+"
{} Exactly the specified number of occurrences "al{2}"
| Either or "falls|stays"
() Capture and group

Let’s discuss each of these metacharacters in detail.
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Regular Expressions

25  [] Square Brackets
Square Brackets ([]) represents a character class consisting of a set of
characters that we wish to match.
For example, the character class [abc] will match any single a, b, or c.
We can also specify a range of characters using – inside the square
brackets.
For example:
 [0, 3] is sample as [0123]
 [a-c] is same as [abc]
We can also invert the character class using the caret(^) symbol.
For example,
[^0-3] means any number except 0, 1, 2, or 3.
[^a-c] means any character except a, b, or c.
 . Dot
Dot(.) symbol matches only a single character except for the newline
charact er (\n).
For example:
a.b will check for the string that contains any character at the place
of the dot such as acb, acbd, abbb, etc.
It will check if the string contains at least 2 characters.
 ^ Caret
Caret (^) symbol matches the beginning of the strin g i.e. checks whether
the string starts with the given character(s) or not.
For example:
^g will check if the string starts with g such asglobe, girl, g, etc.
^ge will check if the string starts with ge such as geeks, geeksandgeek
etc.
 $ Dollar
Dollar($) symbol matches the end of the string i.e checks whether the
string ends with the given character(s) or not.
For example :
s$ will check for the string that ends with geeks, ends, s, etc. munotes.in

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Programming with Python – II
26 ks$ will check for the string that ends with ks such as geeks,
geeks andgeeks, ks, etc.
 | Or
Or symbol works as the or operator meaning it checks whether the
pattern before or after the or symbol is present in the string or not.
For example:
a|b will match any string that contains a or b such as acd, bcd, abcd, etc.
 ? Ques tion Mark
Question mark(?) checks if the string before the question mark in the
regex occurs at least once or not at all.
For example:
ab?c will be matched for the string ac, acb, dabc but will not be
matched for abbc because there are two b.
Similarly, it will not be matched for abdc because b is not followed
by c.
 Star
Star (*) symbol matches zero or more occurrences of the regex preceding
the * symbol.
For example:
ab*c will be matched for the string ac, abc, abbbc, dabc, etc. but will
not be matched for abdc because b is not followed by c.
 + Plus
Plus (+) symbol matches one or more occurrences of the regex preceding
the + symbol.
For example:
ab+c will be matched for the string abc, abbc, dabc, but will not be
matched for ac, abdc because there is n o b in ac and d is not followed
by c in abdc.
 {m, n} – Braces
Braces matches any repetitions preceding regex from m to n both
inclusive.


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Regular Expressions

27 For example :
a{2, 4} will be matched for the string aaab, baaaac, gaad, but will not
be matched for strings like abc, bc because there is only one a or no a
in both the cases.
 () – Group
Group symbol is used to group sub -patterns.
For example :
(a|b)cd will match for strings like acd, abcd, gacd, etc.
3.4 SPECIAL SEQUENCES
A special sequence is a \ followed by one of the characters in the list
below, and has a special meaning:
Character Description Example
\A Returns a match if the specified characters are
at the beginning of the string. "\AThe"
\b Returns a match where the specified
characters are at the beginning or at the end of
a word (the "r" in the beginning is making sure that
the string is being treated as a "raw string") r"\bain"
r"ain \b"
\B Returns a match where the specified
characters are present, but NOT at the
beginning (or at the end) of a word (the "r" in the beginning is making sure that
the string is being treated as a "raw string") r"\Bain"
r"ain \B"
\d Returns a match where the string contains
digits (numbers from 0 -9) "\d"
\D Returns a match where the string DOES NOT
contain digits "\D"
\s Returns a match where the string contains a
white space character "\s"
\S Returns a match where the string DOES NOT
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28 \w Returns a match where the string contains any
word characters (characters from a to Z, digits
from 0 -9, and the underscore _ character) "\w"
\W Returns a match where the string DOES NOT
contain any word characters "\W"
\Z Returns a match if the specified characters are
at the end of the string "Spain \Z"
3.5 SETS
A set is a set of characters inside a pair of square brackets [] with a special
meaning:
Set Description
[arn] Returns a match where one of the specified characters ( a, r,
or n) are present.
[a-n] Returns a match for any lower -case character, alphabetically
between a and n.
[^arn] Returns a match for any character EXCEPT a, r, and n.
[0123] Returns a match where any of the specified digits ( 0, 1, 2,
or 3) are present.
[0-9] Returns a match for any digit between 0 and 9.
[0-5][0-9] Returns a match for any two -digit numbers from 00 and 59.
[a-zA-Z] Returns a match for any character alphabetically
between a and z, lower case OR upper case.
[+] In sets, +, *, ., |, (), $,{} has no special meaning,
so [+] means: return a match for any + character in the string.



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Regular Expressions

29  The findall() Function
The findall() function returns a list containing all matches.
Example 3.2 Print a list of all matches

Output:

The list contains the matches in the order they are found.
If no matches are found, an empty list is returned:
Example 3.3 Return an empty list if no match was found

Output:

 The search() Function
The search( ) function searches the string for a match, and returns a Match
object if there is a match. munotes.in

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30 If there is more than one match, only the first occurrence of the match will
be returned.
Example 3.4 Search for the first white -space character in the string

Output:

If no matches are found, the value None is returned:
Example 3.5 Make a search that returns no match

Output:

 The split() Function
The split() function returns a list where the string has been split at each
match.





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Regular Expressions

31 Example 3.6 Split at each white -space character

Output:

Example 3.7 Split the string only at the first occurrence

Output:

 The sub() Function
The sub() function replaces the matches with the text of your choice.
Example 3.8 Replace every white -space character with the number 9

Output:

You can control the number of replacements by specifying
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32 Example 3.9 Replace the first 2 occurrences

Output:

 Match Object
A Match Object is an object containing information about the search and
the result.
Note:
If there is no match, the value None will be returned, instead of the Match
Object .
Example 3.10 Do a search that will return a Match Object

Output:

The Match object has properties and methods used to retrieve information
about the search, and the result:
.span() - returns a tuple containing the startand end positions of the match.
.string - returns the string passed into the function.
.group() -returns the part of the string where there was a match.
Example 3.11 Print the position (start - and end -position) of the first
match occurrence.
The regular expression looks for any words that starts with an upper case
"S". munotes.in

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33

Output:

Example 3.12 Print the string passed into the function

Output:

Example 3.13 Print the part of the string where there was a match.
The regular expression looks for any words that starts with an upper case
"S":

Output:

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34 UNIT -II
4
GUI PROGRAMMING IN PYTHON -I
Unit Structure
4.0 Objective
4.1 Introduction
4.2 What is GUI
4.3 Advantages of GUI
4.4 Introduction to GUI library
4.5 Layout management
4.6 Events and bindings
4.7 Fonts
4.8 Colors
4.9 Summary
4.10 Reference for further reading
4.11 Unit End Exercises

4.0 OBJECTIVE

 Understand GUI Programming
 Understand concept of window and main loop
 Understand different widget
 Understand menu driven programming

4.1 INTRODUCTION
The graphical user interface (GUI), developed in the late 1970s by
the Xerox Palo Alto research laboratory and Apple’s Macintosh and
Microsoft’s Windows, was designed.

4.2 WHAT IS GUI
Graphical user interfaces (GUI) would bec ome the standard of
user-centered design in software application programming, providing
users to operate computers through the direct manipulation of graphical
icons such as Text box, Buttons, Scroll bars, Spin box, Windows, Radio
Button, Menus, and Cursor s etc.
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35
4.3 ADVANTAGES OF GUI
1. GUI is very user -friendly
2. GUI is more attractive and multi -colored.
3. It is much easy than the command -driven interface
4. User can switch easily between tasks on the GUI interface
Disadvantages of GUI:
1. It becomes complex if the user needs to communicate with the
computer directly
2. It is fully based applications require more RAM .
3. GUI uses more processing power compared to other interface types
4.4 INTRODUCTION TO GUI LIBRARY
Tkinter is the standard GUI library for Python. Python w hen combined
with Tkinter provides a fast and easy way to create GUI applications.
Python provides various options for developing graphical user interfaces
(GUIs) such as Tkinter, wxPython, JPython.

Tkinter − Tkinter is the Python interface to the Tk GUI toolkit shipped
with Python.

wxPython − This is an open -source Python interface for wxWindows
http://wxpython.org .

JPython − JPython is a Python port for Java which gives Python scripts.
Tkinter Programming:

Tkinter is the standard GUI library for Python. Tkinter provides a easy as
well as fast way to create GUI applications. Tkinter provides a powerful
object -oriented interface to the Tk GUI toolkit.

Creating a GUI application using Tkinter you need to do th e following
steps −
Import the Tkinter module.
Create the GUI application main window.

Add one or more of the above -mentioned widgets to the GUI application.
Enter the main event loop to take action against each event triggered by
the user.

Importing Tki nter:

How to import Tkinter?
To import the Tkinter, use the import statement and write the
tkinter and create iGts object. Call the Tk() GUI Kit. Call the
mainloop() method from the Tk(). munotes.in

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36 Example: -
>>> import tkinter as x
>>> a=x.Tk()
>>>a.mainloop()

Output

4.5 LAYOUT MANAGEMENT
Tkinter has three built -in layout managers: the pack , grid , and place
managers. The place geometry manager positions widgets using absolute
positioning. The pack geometry manager organizes widgets in horizontal
and vertical boxes. The grid geometry manager places widgets in a two
dimensional grid.
1. Pack method()
The pack method of geometry manager organizes the widget in
blocks before the appear on the parent widget.
Syntax:
Widget.pack(pack option);
There are three option of pack method and they are expand, fill and side
Expand – if the value of expand o ption is set to true then widget expand to
fill any space. If the value of expand option is set to False then it is used in
widget’s parent.

Fill- The fill option is used to fill any extra space allocated to it by packer.
The fill method has its own minim al dimensions and they are NONE, X
(horizontally), Y (vertically) or Both (Vertical and Horizontal)

Side- It find out which side of the parent widget packs against : TOP ,
BOTTOm, LEFT or RIGHT.
Example -
fromtkinter import *
r = Tk()
r.geometry('350x300+1 20+100')
l1 = Label(r, text="Python", bg="#E74C3C", fg="white").pack(fill=X,
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37 l2 = Label(r, text="JAVA", bg="#2ECC71", fg="black").pack(fill=X,
padx=12)
l3 = Label(r, text="Database", bg="#F1C40F", fg="white").pack(fill=X,
padx=12)
l4 = Label(r, te xt="Python GUI", bg="#34495E", fg="white").pack(fill=X,
padx=12, pady=12, side=LEFT)
l5 = Label(r, text="Python Database", bg="#5DADE2",
fg="black").pack(fill=X, padx=12, side=LEFT)
l6 = Label(r, text="Python Networking", bg="#A569BD",
fg="white").pack(fil l=X, padx=12, side=LEFT)
listbox = Listbox()
listbox.pack(fill=BOTH, expand=1)
for i in range(10):
listbox.insert(END, str(i))
mainloop()

Output:


Grid method:
Grid method geometry manager is used to organize widgets in a table like
structure in the parent widget.

Syntax:
Widget.grid(options)
There are following option
Column : It is a column to put widget in default 0.
Columnspan : This tells that how many columns widget occupies. The
default value is 1.
Row : it is a row to put widget in. default t he first row that is still empty.
Rowspan : it tells how many row widget have occupied, be default is is 1.
Example:
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38 Label(text="Rollno", width=10).grid(row=0, column=0)
Label(text="Name", width=10).grid(row=0, column=1)
Label(text="Ag e", width=10).grid(row=0, column=2)
Label(text="1001", width=10).grid(row=1, column=0)
Label(text="Sandeep", width=10).grid(row=1, column=1)
Label(text="18", width=10).grid(row=1, column=2)
Label(text="1003", width=10).grid(row=2, column=0)
Label(text="Sac hin", width=10).grid(row=2, column=1)
Label(text="17", width=10).grid(row=2, column=2)
Label(text="1005", width=10).grid(row=3, column=0)
Label(text="Deepak", width=10).grid(row=3, column=1)
Label(text="19", width=10).grid(row=3, column=2)
Label( text="1012", width=10).grid(row=4, column=0)
Label(text="Rajesh", width=10).grid(row=4, column=1)
Label(text="21", width=10).grid(row=4, column=2)
mainloop()

Output:


Place()
The place() method of layout manager organizes widgets in the parent
widget by placing them in a specific position.

Syntax:
widget.place(place option)

The following option:
Anchor – The exact spot of widget other option refer to may ne N,E, S, W,
NE, NW, SE or SW, compass directions indicating the corners and sides
od widget: defa ult is NW.

Bordermode – INSIDE to indicate that other option refer to the parent’s
inside, OUTSIDE otherwise.

Height, width - It determines the height and width in pixel.
X,y – It determines horizontal and vertical offset in pixcel.
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39 root = Tk()
Label(root, text="Rollno is : 1090 ").place(x=10, y=20)
Label(root, text="Name is : Sandeep ").place(x=10, y=60)
Label(root, text="Age : 18 ").place(x=10, y=100)
Label(root, text="DOB : 31 March 2005 ").place(x=10, y=140)
Label(root, text="Location is : Mumbai ").place(x=10, y=180)
Label(root, text="University is : Mumbai University ", bg="red",
fg="white").place(x=10, y=220)
mainloop()
Output:

4.6 EVENTS AND BINDINGS
Events and bindings plays important role in events handing in
python.Widget configuration and styling is also vital in GUI.
To bind an event to any widget in python , bind() is used.
Syntax
widget.bind(event,handler)
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40 handler can be type of button or key used to han dle event
Whenever event occurs the handler is called to execute particular function
related to the event.
Example:
fromtkinter import *
defadditon():
res=int(n1.get())+int(n2.get())
mt.set(res)
m = Tk()
mt=StringVar()
Label(m, text="Enter First Number "). grid(row=0, sticky=W)
Label(m, text="Enter Second Number ").grid(row=1, sticky=W)
Label(m, text="Addition is :").grid(row=3, sticky=W)
result=Label(m, text="", textvariable=mt).grid(row=3,column=1,
sticky=W)
n1 = Entry(m)
n2 = Entry(m)
n1.grid(row=0, column=1)
n2.grid(row=1, column=1)
b = Button(m, text="Click for Addition", command=additon)
b.grid(row=0, column=2,columnspan=2, rowspan=2)
mainloop()
output:

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41 Events
Tkinter provides a powerful mechanism to deal with events. For each
widget, you can bind python functions and methods to events. If an event
matching the event description occurs in the widget, the given handler is
called with an object describing the event.
The event sequence is given as a string, using the following:
Syntax
(modifier -type-detail)
The type field is the essential part of an event specifier, whereas the
“modifier” and “detail” fields are not obligatory and are left out in many
cases. They are used to provide additional information for the chosen
“type”. The event “type” des cribes the kind of event to be bound, e.g.
actions like mouse clicks, key presses or the widget got the input focus.
Events and its Description
- A mouse button is pressed with the mouse pointer over the
widget. If you press down a mouse button o ver a widget and keep it
pressed.
(x,y) - The mouse is moved with a mouse button being held
down.The current position of the mouse pointer is provided in the x and y
members of the event object passed to the callback, i.e. event.x, event.y
- Event, if a button is released.
The current position of the mouse pointer is provided in the x and y
members of the event object passed to the callback, i.e. event.x, event.y
- Similar to the Button event, see above, but the button is
double clicked instead of a single click
Class bindings
The bind method we used in the above example creates an instance
binding. This means that the binding applies to a single widget only; if you
create new frames, they will not inherit the bindings.
But Tkinter also allows you to create bindings on the class and application
level
Example:
fromtkinter import *
def function1(event):
print("Single Click on Button ,Button -l")
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42 print( "Double Click on Button")
import sys; sys.exit()
widget = Button(None, text='Mouse Clicks')
widget.pack()
widget.bind('', function1)
widget.bind('', function2)
widget.mainloop()
Output:

4.7 FONTS
The Simple Tuple fonts are commonly use for specify the font. The
tuple contains first element font family, Second element size in points
and third element style modifiers like underline, bold etc.
Example:
(“Arial”,”28”,”bold”
For Font object Fonts
User can create a font object by importin g the tkFont and using its font
class constructor.
Import tkFont
Font= tkFont.Font(option…)
Option are:
Family – It is the font family name as a string
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43 Weight – it uses “bold” for boldface
Underline use 1 for underline, 0 for normal
Example
X=tkFont.Font(family=”Arial”, size=14, weight=”bold”)

4.8 COLORS
Standard attributes and properties of Widgets -
There are some common attributes like color, size, and font.
Color:
Color is represented in the string f ormat. User can specify the color in the
following:
Name
User can use any locally defined standard color name like “red”, “green”,
“white”, “black”, “green” etc.
Hexadecimal unit
Instead of color name use hexadecimal digit like ‘#fff’ for white, ‘#00000’
for balck, ‘#000fff000’ for pure green.
Color option
The following color option
activebackground - It is used to set Background color for the active
widget
activeforeground - It is used to set foreground color for the active widget
Background – bg is used t o set background color for the active widget
highlightbackground – bg is used to set background color for the highlight
region when the widget has focus.
highlightcolor – It is used to set the foreground color for the highlight
region when the widget has focus.
Selectbackground - It is used to set the background color for the selected
item of the widget.
Selectforeground - It is used to set the foreground color for the selected
item of the widget.
disabledforeground - It is used to set foreground color for the disable
widget
Foreground – fg is used to set foreground color for the active widget




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44 4.9 SUMMARY
1. GUI is more attractive and multi -colored.
2. Tkinter is the standard GUI library for Python. Python when combined
with
3. Tkinter provides a fast and easy way to create GUI applications.
Tkinter has three built -in layout managers: the pack , grid , and place
managers.
4.10 REFERENCE FOR FURTHER READING

1. Paul Gries , Jennifer Campbell, Jason Montojo, Practical
Programming: An Introduction to Computer Science Using Python 3 ,
Pragmatic Bookshelf, 2/E 2014
2. James Payne , Beginning Python: Using Python 2.6 and Python 3,
Wiley India, 2010
4.11 UNIT END EXERCISES

1. Explain the layout management features.
2. Explain bind with example
3. Explain color in GUI.
4. Explain Font in GUI.
5. Write a program for addition and multiplication of two number using
Entry




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45 5
GUI PROGRAMMING IN PYTHON -II
Unit Structure
5.0 Objective
5.1 Introduction
5.2 Drawing on canvas:
a. line,
b. oval,
c. rectangle
5.3 Widgets such as :
d. frame,
e. label,
f. button,
g. check button,
h. entry,
i. list box,
j. message,
k. radio button,
l. text,
m. spin box
5.4 Summary
5.5 Reference for further reading
5.6 Unit End Exercises
5.0 OBJECTIVE
 Understand canvas, frame, Label
 Understand concept of Entry, Message, List
 Understand Check button, Button
 Understand Radio Button, Text etc
5.1 INTRODUCTION
Graphical user interfaces (GUI) would become the standard of
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46 users to operate computers through the direct manipulation of graphical
icons such as Text box, Buttons, Scroll bars, Spin box etc.
5.2 DRAWING ON CANVAS:
a. line
The create_line method creates a line item on the Canvas .
Example:
fromtkinter import *
t = Tk()
C = Canvas(t, bg="green", height=350, width=400)
coord = 10, 50, 240, 210
arc = C.create_line(55, 85, 155, 85, 105, 180, 55, 85)
C.pack()
t.mainloop()
output :

b. oval
The create_oval() method is used to create a circle item. The first
four parameters are the bounding box coordinates of the circle. In other
words, they are x and y coordinates of the top -left and bottom -right points
of the box, in which the circle is drawn.
Example:
fromtkinter import *
t = Tk()
C = Canvas(t, bg="green", height=350, width=400)
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47 arc = C.create_oval(10, 10, 350, 200, width=1)
C.pack()
t.mainloop()
output:

c. rectangle
To create a rectangle create_rectangle() method is used.
This method accepts 4 parameters x1, y1, x2, y2. Here x1 and y1 are
the coordinates for the top left corner and x2 and y2 are the
coordinates for the bottom right corner.
Example:
fromtkinter import *
t = Tk()
C = Canvas(t, bg="green", height=350, width=400)
coord = 10, 50, 240, 210
arc = C.create_rectangle(50, 50, 290, 260, width=2)
C.pack()
t.mainloop()
output:
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48 2. Widgets such as :
a. Frame
The frame widget is used to group the widget in a friendly way. Its helps
to look the GUI organized. It is like a container which arranges the
position of the other widget .
Syntax:
F=Frame (master, option)
Example:
fromtkinter import *
root = Tk()
frame = Frame(root)
frame.pack()
bottomframe = Frame(root)
bottomframe.pack( side = BOTTOM )
button1 = Button(frame, text="Add", fg="green")
button1.pack( side = LEFT)
button2 = Button(frame, text="Div", fg="brown")
button2.pack( side = LEFT )
button3 = Bu tton(frame, text="Sub", fg="blue")
button3.pack( side = LEFT )
button4 = Button(bottomframe, text="Multi", fg="black")
button4.pack( side = BOTTOM)
root.mainloop()

Output:

b. Label
Labels
The label widget is a display box where we can place text or images. We
can change label text any time we want . If we want to underline the text
we can do that and also we can span text across multiple lines

Syntax
Simple syntax to create this widget −
x = Label ( master, option, ... )

The argument master represents the parent window and the argument
option is the option used by label widget as a key -value pairs and they are
separated by comma.

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49
The list of most commonly used options for this widget

Anchor This options controls where the text is positioned. The
default is anchor=CENTER.
Bg The background color displayed behind the label.
Bd The size of the border around. Default is 2 pixels.
Font The font option specifies in what font that text will be
displayed.
Image To display a static image in the label widget.
Width Width of the label in characters.

Example:
importtkinter as tk
r = tk.Tk()
x = tk.Label(r, text="Hello Student ")
x.pack()
r.mainloop()
output

Example 2:
importtkinter as tk
r = tk.Tk()
tk.Label(r,
text="Mumbai University",
fg = "red",
font = "Times").pack()
tk.Label(r,
text="python programming",
fg = "light green",
bg = "dark green",
font = "Helvetica 16 bold italic").pack()
tk.Label(r,
text="object oriented programming python",
fg = "blue",
bg = "yellow",
font = "Verdana 14 bold").pack()
r.mainloop()

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50 Output:



Example:
importtkinter as tk
r = tk.Tk()
img1 = tk.PhotoImage(file="python123.gif")
txt = "Hi, Student "
w = tk.Label(r, compound = tk.CENTER,
text=txt,
image=img1).pack(side="right")
r.mainloop()
output:


c. Button
Labels
The label widget is a display box where we can place text or images. We
can change label text any time we want . If we want to underline the text
we can do that and also we can span text across multiple lines
Syntax
Simple syntax to create this widget −
x = Label ( master, option, ... )
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51 The argument master represents the parent window and the argument
option is the option used by label widget as a key -value pairs and they are
separated by comma.

The list of most commonly used options for this widget

Anchor This options controls where the text is positioned. The
default is anchor=CENTER.
Bg The background color displayed behind the label.
Bd The size of the border around. Default is 2 pixels.
Font The font option specifies in what font that text will be
displayed.
Image To display a static image in the label widget.
Width Width of the label in characters.

Example:
importtkinter as tk
r = tk.Tk()
x = tk.Label(r, text="Hello Student ")
x.pack ()
r.mainloop()
output

Example 2:
importtkinter as tk
r = tk.Tk()
tk.Label(r,
text="Mumbai University",
fg = "red",
font = "Times").pack()
tk.Label(r,
text="python programming",
fg = "light green",
bg = "dark green",
font = "Helvetica 16 bold italic").pack()
tk.Label(r,
text="object oriented programming python",
fg = "blue",
bg = "yellow",
font = "Verdana 14 bold").pack()

r.mainloop()
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52 Output:



Example:
importtkinter as tk
r = tk.Tk()
img1 = tk.PhotoImage(file ="python123.gif")
txt = "Hi, Student "
w = tk.Label(r, compound = tk.CENTER,
text=txt,
image=img1).pack(side="right")
r.mainloop()

Output :


d. check button,
The Checkbutton widget is used to display a number of options to a
user as toggle buttons. The user can then select one or more options
by clicking the button.
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53 Syntax
w = Checkbutton( master, option, ... )
Example
fromtkinter import *
r = Tk()
C1 = Checkbutton(r, text = "Python")
C2 = Checkbutton(r, text = "Java")
C3 = Checkbutton(r, text = "C++")
C4 = Checkbutton(r, text = "HTML")
C1.pack()
C2.pack()
C3.pack()
C4.pack()
r.mainloop()
Output:

e. entry
The Entry widget accepts single line text strings.
Syntax
e = Entry( master, option, ... )
Parameters
master − This represents the parent window.
options − These options can be used as key -value pairs separated by
commas.
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54
Option Description
Font The font used for the text.
Command A procedure to be called every time the user
changes the state of this check button.
Bg The normal background color displayed behind the
label and indicator.
Bd The size of the border around the indicator. Default
is 2 pixels.
exportselection By default, if you select text within an Entry
widget, it is automatically exported to the
clipboard. To avoid this exportation, use
exportselection=0.
Justify If the text contains multiple lines, this option
controls how the text is justified: CENTER, LEFT,
or RIGHT.

List of methods are commonly used for this widget –
Methods Description
get() Returns the entry's current text as a string.
icursor ( index ) Set the insertion cursor just before the character at
the given index.
insert ( index, s ) Inserts string s before the character at the given
index.
select_clear() Clears the selection.
select_range ( start,
end ) Selects the text starting at the start index, up to but
not including the character at the end index.

Example :
fromtkinter import *
t = Tk()
l1= Label( t, text="Enter Your Rollno")
l1.pack(side = LEFT)
e1 = Entry(t,bd=12)
e1.pack(side = RIGHT)
t.mainloop()


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55 Output :

f. list box
The listbox widget displays a list of items. The user can select the item
from the given list. ListBox can display different types of items. These
items must be of the same type of font and color. The user can select one
or more items from the given list according to the requirement.
Syntax
L=Listbox(master, option,…)
The argument master represents the par ent window and the argument
option is the option used by Listbox widget as a key -value pairs and they
separated by comma.
Methods on listbox:
activate ( index ) Selects the line specifies by the index.
get ( first, last=None
) Returns a values containing the text of the lines
with indices from first to last
curselection() Returns values containing the line numbers of the
selected element or elements, counting from zero.
delete ( first,
last=None ) Deletes the lines whose indices are in the range
[first, last]

Example:
fromtkinter import *
t = Tk()
Lb1 = Listbox(t)
Lb1.insert(1, "Mumbai")
Lb1.insert(2, "Thane")
Lb1.insert(3, "Pune")
Lb1.insert(4, "Nashik")
Lb1.insert(5, "Nagpur")
Lb1.pack()
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56 Output

g. message
It is GUI element of tkinter. It is multiline and non -editable object. It
displays the static text. If length of message is large, it automatically
breaks the long text to multiple lines. It is similar to label widget. The only
difference is the message widget automatically wraps the text where the
label widget does not do automatically.
Syntax:
M=Message(master, option)
The argument master represents the parent window and the argument
option is the option used by message widget as a key -value pairs and they
separated by comma.
Example:
fromtkinter import *
t = Tk()
var1 = StringVar()
label1 = Message( t, textvariable=var1, relief=RAISED )
var1.set("It is GUI element of tkinter. It is multiline and non -editable
object.")
label1.pack()
t.mainloop()
Output:

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57 h. radio button
The radio button is also known as option button. The option button allows
user to select values from the predefined set of values. Radio button
contains text as well as image. We can associate the function with the
option button when we select the option the function is cal led
automatically.

Methods use in Radio Button
Methods Description
select() Sets the radiobutton.
deselect() Clears the radiobutton.
invoke() You can call this method to get the same actions
that would occur if the user clicked on the option
button to change its state.

Example:
fromtkinter import *
t = Tk()
def function1():
selection = "selected your subject " + str(var1.get())
label.config(text = selection)
var1 = IntVar()
R1 = Radiobutton(t, text="Python", variable=var1, value=1,
command=function1)
R1.pack( anchor = W )
R2 = Radiobutton(t, text="Java", variable=var1, value=2,
command=function1)
R2.pack( anchor = W )
R3 = Radiobutton(t, text="perl", variable=var1, value=3,
command=function1)
R3.pack( anchor = W)
label = Label(root)
label.pack()
t.main loop()




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58 Output :



i. text
Text widget allows user to edit the multiline text. User can also format the
text the way user want to it display. User can change the color of the text,
foreground color as well as background color for the text and also user can
set the font of the text.
Syntax:
T= Text(master, option,…)
Method
Text object have following methods
Method Description
Get() This method returns a specific character of text.
Insert() This method inserts strings at the specified index
location.
See(index) This method returns true if the text located at the
index position is visible.
Index() Returns the absolute value of an index based on
the given index.
Example:
fromtkinter import *
t = Tk()
defonclick():
pass
text = Text(t)
text.insert( INSERT, "Mumbai")
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59 text.tag_add("123", "1.0", "1.4")
text.tag_add("444", "1.8", "1.13")
text.tag_config("123", background="yellow", foreground="red")
text.tag_config("444", background="black", foreground="blue")
t.mainloop()
Output:

j. spin box
The spinbox contains the fixed number of values and it allows selecting
the value from the given values. It is a standard Tkinter Entry eidget.
Syntax:
s = Spinbox( master, option )
The argument master represents the parent wi ndow and the argument
option is the option used by message widget as a key -value pairs and they
separated by comma.
Option Description
from_ The minimum value.
Justify Default is LEFT
State One of NORMAL, DISABLED, or
"readonly".
To See from.
Validate Validation mode. Default is none
Width Widget width, in character units. Default is
20.

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60 Example
fromtkinter import *
t = Tk()
s = Spinbox(t, from_=0, to=10)
s.pack()
b.pack()
Output

5.4 SUMMARY

 In this chapter we studied the GUI programming with different widget.
 Widget such as Button, Text, List, Radio button etc. call function
when user clicks on button and different widget.
5.5 REFERENCE FOR FURTHER READING

1. Mastering GUI Programming with Python: Develop impressive cross -
platform.
2. Python GUI Pr ogramming with Tkinter: Develop responsive and
powerful GUI applications with Tkinter
5.6 UNIT END EXERCISES

1. Explain Menu widget with Example
2. Write a program for Addition of two number using tkinter.
3. Write a program for factorial of given number using tkinter.
4. Explain any three widget.
5. Explain tkMessagebox module
6. Explain PanedWindow and Toplevel widget
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61 UNIT -III
6
DATABASE & NETWORKING
CONNECTIVITY
Unit Structure
6.0 Objective
6.1 Introduction
6.2 Database connectivity in Python :
a. Installing mysql connector,
b. accessing connector module,
c. using connect,
d. cursor,
e. execute & close functions,
f. reading single & multiple results of query execution,
g. executing different types of statements,
h. executing transactions,
i. Understanding exceptions in database connectivity.
6.3 Network connectivity :
j. Socket module,
k. creating server -client programs,
l. sending email,
m. reading from URL
6.4 Summary
6.5 Reference for further reading
6.6 Unit End Exercises
6.0 OBJECTIVE
 Understand Python and connector installation
 Understand concept of database
 Understand Create table, insert record
 Understand how the record are delete, update etc
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62 6.1 INTRODUCTION
Python supports various databases like MySQL, Oracle, Sybase, Postgre
SQL, etc. Python also supports Data Definition Language (DDL), Data
Manipulation Language ( DML) and Data Query Statements. For database
programming, the Python DB API is a widely used module that provides a
database application programming interface.
6.2 DATABASE CONNECTIVITY IN PYTHON :
a. Installing mysql connector,
Connector/Python Installation
Connector/Python runs on any platform where Python is installed. Python
comes preinstalled on most Unix and Unix -like systems, such as Linux,
macOS, and FreeBSD. On Microsoft Windows, a Python installer is
available at the Python Download website. If nece ssary, download and
install Python for Windows before attempting to install Connector/Python.
Connector/Python implements the MySQL client/server protocol two
ways:
• As pure Python; an implementation written in Python. Its
dependencies are the Python Stan dard Library and Python Protobuf>=
3.0.0.
• As a C Extension that interfaces with the MySQL C client library. This
implementation of the protocol is dependent on the client library, but
can use the library provided by MySQL Server packages (see MySQL
C API Implementations).

Obtaining Connector/Python
Packages are available at the Connector/Python download site. For some
packaging formats, there are different packages for different versions of
Python; choose the one appropriate for the version of Python ins talled on
your system.

Installing Connector/Python from a Binary Distribution
Connector/Python installers in native package formats are available for
Windows and for Unix and Unix -like systems:

• Windows: MSI installer package
• Linux: RPM packages for O racle Linux, Red Hat, and SuSE;
• macOS: Disk image package with PKG installer

You may need root or administrator privileges to perform the
installation operation.

Binary distributions that provide the C Extension link to an already
installed C client library provided by a MySQL Server installation. For
those distributions that are not statically linked, you must install MySQL munotes.in

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63 Server if it is not already present on y our system. To obtain it, visit the
MySQL download site.

Installing Connector/Python on Microsoft Windows
Managing all of your MySQL products, including MySQL
Connector/Python, with MySQL Installer is the recommended approach. It
handles all requirements and prerequisites, configurations, and upgrades.

Prerequisite. The Microsoft Visual C++ 2015 Redistributable must be
installed on your system.

• MySQL Installer (recommended): When executing MySQL Installer,
choose MySQL Connector/Python as one of the p roducts to install.
MySQL Installer installs the Windows MSI Installer described in this
documentation.

• Windows MSI Installer (.msi file): To use the MSI Installer, launch it
and follow the prompts in the screens it presents to install
Connector/Python in the location of your choosing.

Like with MySQL Installer, subsequent executions of the
Connector/Python MSI enable you to either repair or remove the existing
Connector/Python installation.

Connector/Python Windows MSI Installers (.msi files) are avai lable from
the Connector/Python download site (see Section 4.1, “Obtaining
Connector/Python”). Choose an installer appropriate for the version of
Python installed on your system. As of Connector/Python 2.1.1, MSI
Installers include the C Extension; it need not be installed separately.

Installing Connector/Python from Source on Microsoft Windows
A Connector/Python Zip archive (.zip file) is available from the
Connector/Python download site (see Section 4.1, “Obtaining
Connector/Python”).

To install Connect or/Python from a Zip archive, download the latest
version and follow these steps:

1. Unpack the Zip archive in the intended installation directory (for
example, C: \mysql -connector \) using WinZip or another tool that can
read .zip files.
2. Start a console window and change location to the folder where you
unpacked the Zip archive:
$> cd C: \mysql -connector \
3. Inside the Connector/Python folder, perform the installation using
this command:
$> python setup.py install munotes.in

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64 To include the C Extension (available as of Connector/Python 2.1.1),
use this command instead:
$> python setup.py install --with-mysql -capi="path_name"
The argument to --with-mysql -capi is the path to the installation directory
of MySQL Server.
To see all options and commands supported by setu p.py, use this
command:
$> python setup.py –help

b. accessing connector module,
Configuration file is used to store credentials like permission to database,
table and database related commands to specific users. The configuration
file is used to the MySql se rver and then creates your own database on the
MySql server.

Establishing a Connection with MySQL Server
MySQL is a server -based database management system. One server might
contain multiple databases. To interact with a database, you must first
establish a connection with the server. The general workflow of a Python
program that interacts with a MySQL -based database is as follows:
 Connect to the MySQL server.
 Create a new database.
 Connect to the newly created or an existing database.
 Execute a SQL query and fetch results.
 Inform the database if any changes are made to a table.
 Close the connection to the MySQL server.
c. using connect,
d. cursor, execute & close functions
To execute a SQL query in Python, you’ll need to use a cursor, which
abstracts away the access to database records. MySQL
Connector/Python provides you with the MySQLCursor class, which
instantiates objects that can execute MySQL queries in Python. An
instance of the MySQLCursor class is also called a cursor.

cursor objects make use of a MySQLConnection object to interact with
your MySQL server. To create a cursor, use the .cursor() method of
your connection variable:
cursor = connection.cursor()
Inserting Records in Tables
In the last section, you created three tables in your database: movies,
reviewers, and ratings. Now you need to populate these tables with data. munotes.in

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65 This section will cover two different ways to insert records in the MySQL
Connector for Pyth on.
The first method, .execute(), works well when the number of records is
small and the records can be hard -coded. The second method,
.executemany(), is more popular and is better suited for real -world
scenarios.
Using .execute()
The first approach uses t he same cursor.execute() method that you’ve been
using until now. You write the INSERT INTO query in a string and pass it
to cursor.execute(). You can use this method to insert data into the movies
table.
Reading Records Using the SELECT Statement
To retri eve records, you need to send a SELECT query to cursor.execute().
Then you use cursor.fetchall() to extract the retrieved table in the form of a
list of rows or records.
Filtering Results Using the WHERE Clause
You can filter table records by specific crit eria using the WHERE clause.
For example, to retrieve all movies with a box office collection greater
than $300 million, you could run the following query:
SELECT empno,ename
FROM emp
WHERE salary > 9000;
UPDATE Command
For updating records, MySQL uses the UPDATE statement
DELETE Command
Deleting records works very similarly to updating records. You use the
DELETE statement to remove selected records.
Example for connection:
importmy sql.connector
cnx = mysql.connector.connect(user='abc', password='123',
host='122.0.0.1',
database='xyz')
cnx.close()
Example for Connection using try
importmysql.connector
frommysql.connector import errorcode munotes.in

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66 try:
cnx1 = mysql.connector.connect(user='a bc',
database='emp1')
exceptmysql.connector.Error as err1:
if err1.errno == errorcode.ER_ACCESS_DENIED_ERROR:
print("wrong user name or password")
elif err1.errno == errorcode.ER_BAD_DB_ERROR:
print("Database not found")
else:
print(err1)
else:
cnx1.close( )
Create dictionary to hold connection information
dbConfig={
‘user’:, #your Admin Nmae
‘password’:,#admin password
‘host’:122.0.0.1,#local host ip address
}
For creating own database use following commands
GUID=”GuiDB”
Conn= mysql.connect(**guiConf.dbConfig)
Cursor.conn.cursor()
try:
cursor.execute(:CREATE DATABSE {} DEFAULT CHARACTER SET
‘utf8’”.
Format(GUIDB))
Except mysql.Error as err:
Print(“Failed to create database{}”.format(err))
Conn.close()
In the above code we create d the cursor object from connection object to
execute commands to MYSQL. A cursor is usually a place in a definite
row in a database table.
e. Reading single & multiple results of query execution, executing
different types of statements,executing transactions , Understanding
exceptions in database connectivity.
Retrieving record from table we used select command. where clause are
used with select command for matching particular condition. munotes.in

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67 Syntax:
Select Field No1, Field No 2,
From

Where Condition.
Example
importmysql.connector
try:
connection = mysql.connector.connect(host='localhost',
database='db1',
user='abc',
password='123')
sql = "select * from Student"
cursor = connection.cursor()
cursor.execute(sql)
records = cursor.fetchall()
print( "Total number of records ", cursor.rowcount)
print(" \nPrinting each row")
for row in records:
print("Student_ID = ", row[0], )
print("Student Name = ", row[1])
print("Phy = ", row[2])
print("Chem = ", row[2])
print("Bio = ", row[3], " \n")
exceptmysql.c onnector.Error as e:
print("Error reading data", e)
finally:
ifconnection.is_connected():
connection.close()
cursor.close()
Show database command:
Import mysql.connector as mysql
Import GuiDBConfig as guiCon
Conn=mysql.connect(**guiConfig.dbConfig)
Cursor= conn.cursor()
Cursor.execute(“SHOW DATABASE” ) munotes.in

Set where < Condition>
Import MySQLdb
db=MYSQLdb.connect(“localhost”,”abc”,”123”,”database1”)
Cursor=db.cursor()
Sql=”UPDATE STUDENT
Set Phy=67
Where Student_Id=101”
munotes.in

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70 try:
cursor.execute(sql)
db.commit()
except
db.rollback()
db.close()
Example for update all record in table
Update chemistry subject marks by 10% of each student
Import MySQLdb
db=MYSQLdb.connect(“localhost”,”abc”,”123”,”database1”)
Cursor=db.cursor()
Sql=”UPDATE STUDENT
Set chem=chem*.010”
try:
cursor.execute(sql)
db.commit()
except
db.rollback()
db.close()
DELETE Command
DELETE command is use for delete record from table. To delete
particular record we used where with condition.
Syntax:
DELETE FROM

Where Condition.
Example:
Import MySQLdb
db=MYSQLdb.connect (“localhost”,”abc”,”123”,”database1”)
Cursor=db.cursor()
Sql=”DELETE FROM STUDENT
Where Student_Id=101”
try:
cursor.execute(sql)
db.commit()
except munotes.in