‘How to develop Pythonic coding rather than Python coding – Logic Perspective’

Online Workshop on ‘How to develop
Pythonic coding rather than Python
coding – Logic Perspective’
21.7.20 Day 1 session 1
Dr. S.Mohideen Badhusha
Professor/ CSE department
Alva’s Institute Engineering and
Technology
Mijar, Moodbidri, Mangalore
1

2
Basics of
Python Programming

3
To acquire knowledge in basic programming
constructs in Python
To comprehend the concept of functions in Python
To practice the simple problems in programming
constructs and functions in Python
Objectives of the Day 1 session 1

4
Introduction to Python
• Python - a general-purpose,Interpreted,
interactive, object-oriented and high-level
programming language.
• Fastest growing open source Programming
language
• Dynamically typed
• Versatile and can be adapted in DA,
ML,GUI,Software &Web development
• It was created by Guido van Rossum during
1985-1990.
4

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Python IDEs
• IDLE
• Pycharm
• Spyder
• Thonny
• Atom
• Anaconda -Jupyter Notebook, Ipython
for larger project in different domains.
• Google colab
5

6
6
Anaconda activated Jupyter
notebook/google colab

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Comment lines
• Single comment line is # comment line
• Multiple comment lines triple single quotes or
triple double quotes ‘’’ or “””
• ‘’’ multiple comment lines
……
…. ‘’’
“““ This is the Program for blah
blah blah.- multiple comment line”””
# This is a program for adding 2 nos
7

8
Multiple Assignment
• You can also assign to multiple names at the
same time.
>>> x, y = 2, 3
>>> x
2
>>> y
3
Swapping assignment in Python
x,y=y,x
8

9
Reserved Words
(these words can’t be used as varibles)
9
and exec Not
as finally or
assert for pass
break from print
class global raise
continue if return
def import try
del in while
elif is with
else lambda yield

10
Indentation and Blocks
• Python doesn't use braces({}) to
indicate blocks of code for class and
function definitions or flow control.
• Blocks of code are denoted by line
indentation, which is rigidly enforced.
• All statements within the block must
be indented the same level
10

11
• Python uses white space and indents
to denote blocks of code
• Lines of code that begin a block end in
a colon:
• Lines within the code block are
indented at the same level
• To end a code block, remove the
indentation

12
Dynamically Typed: Python determines the data types
of variable bindings in a program automatically.
But Python’s not casual about types, it
enforces the types of objects.
“Strongly Typed”
So, for example, you can’t just append an integer to a
string. You must first convert the integer to a string
itself.
x = “the answer is ” # Decides x is bound to a string.
y = 23 # Decides y is bound to an integer.
print (x + y) # Python will complain about this.
print (x + str(y)) # correct
Python data types

13
Conditional Execution
• if and else
if v == c:
#do something based on the
condition
else:
#do something based on v != c
• elif allows for additional branching
if condition:
…...
elif another condition:
… 13

14
# python program for finding greater of two numbers
a=int(input(‘Enter the first number’))
b=int(input(‘Enter the second number’))
if a>b:
print("The greater number is",a)
else:
print("The greater number is",b)
# for satisfying equality condition
if a>b:
print("The greater number is",a)
elif a==b:
print(“both numbers are equal",a)
else:
print(“The greater number is",b)

15
Nested conditionals
One conditional can also be nested within
another. We could have written the three-branch
example like this:
a=int(input(‘Enter the first number’))
b=int(input(‘Enter the second number’))
if a==b:
print(“Both the numbers are equal",a)
else:
if a>b:
print(“The greater number is",a)
else:
print(“The greater number is",b)

16
Variables, expressions, and statements
python
>>> print(4)
4
If you are not sure what type a value has, the
interpreter can tell you.
>>> type('Hello, World!')
<class 'str'>
>>> type(17)
<class 'int'>
>>> type(3.2)
<class 'float'>
>>> type('17')
<class 'str'>
>>> type('3.2')
<class 'str'>

17
If you give a variable an illegal name, you get
a syntax error:
>>> 76trombones = 'big parade'
SyntaxError: invalid syntax
>>> more@ = 1000000
>>> class = 'Advanced Theoretical Zymurgy'

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Operators and operands
a=20 b=10
+ Addition Adds values on either side of the
operator.
a + b = 30
- Subtraction Subtracts right hand operand from
left hand operand.
a – b = -10
* Multiplication Multiplies values on either side of
the operator
a * b = 200
/ Division Divides left hand operand by right hand
operand
b / a = 0.5

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// Floor Division - The division of operands where the result
is the quotient in which the digits after the decimal point
are removed.
9//2 = 4 and 9.0//2.0 = 4.0
% Modulus Divides left hand operand by right hand
operand and returns remainder
a % b = 0
** Exponent Performs exponential power calculation on
operators
a**b =20 to the power 10

20
Relational Operators
== equal to
!= or <> not equal to
> greater than
>=greater than or equal to
< less than
<= less than or equal to

21
Python Assignment Operators
= Assigns values from right side operands
to left side operand c = a + b assigns value of a + b into c
+= Add AND It adds right operand to the left operand
and assign the result to left operand
c += a is equivalent to c = c + a
-= Subtract AND It subtracts right operand from the left
operand and assign the result to left operand c -= a is
equivalent to c = c – a
*= Multiply AND It multiplies right operand with the left
operand and assign the result to left operand c *= a is
equivalent to c = c * a

22
/= Divide AND It divides left operand with the right
operand and assign the result to left operand c /= a is
equivalent to c = c / ac /= a is
equivalent to c = c / a
%= Modulus AND It takes modulus using two operands
and assign the result to left operand c %= a is
equivalent to c = c % a
**= Exponent Performs exponential power calculation on
operators and assign value to the left c **= a is
equivalent to c = c ** a

23
The + operator works with strings, but it is not addition
in the mathematical sense.
Instead it performs concatenation, which means joining
the strings by linking them end to end. For example:
>>> first = 10
>>> second = 15
>>> print(first+second)
25
>>> first = '100'
>>> second = '150'
>>> print(first + second)
100150

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Functions
A function is a block of organized, reusable
code that is used to perform a single,
related action.
Functions provide better modularity for
your application and a high degree of code
reusing.

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Syntax for function definition
def functionname( parameters ):
function_suite
return [expression]
Example :
def great2(x,y) :
if x > y :
return x
else:
return y
Special feature of function in Python is that it can return
more than one value

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Calling the Function
def great2(x,y) :
if x > y :
return x
else:
return y
a=int(input(‘Enter a’))
b=int(input(‘Enter b’))
print(‘The greater number is’, great2(a,b))

27
Catching exceptions using try and except
inp = input('Enter Fahrenheit Temperature:')
try:
fahr = float(inp)
cel = (fahr - 32.0) * 5.0 / 9.0
print(cel)
except:
print('Please enter a valid number')

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Concluding Tips
Interpreted ,Object oriented and open sourced
Programming language
Developed by Guido van Rossum during 1985-90
Dynamically typed but strongly typed language
Indented language which has no block level symbols {}
No ; is necessary . Block beginning starts with :
function starts with def key word followed by function
name and :
#- single comment line ’’’ or ””” - multiple comment line
if...else if...elif ...elif No endif
Multiple assignment x,y,z=2,4,5 is possible
/ - divide with precision //- floor division (no precision)

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