Nudge Notes - Python Language Basics

 

1. Datatypes in Python:

• None
• Numeric
• float -> 1.5
• int -> 5
• complex -> 2+5j
• bool -> True/false
• Sequence
• List -> [3,5,6,7,1]
• Tuple -> (3,5,6,7,1)
• Set -> {3,5,6,7,1}
• String -> "Akshay"
• Range 
• range(5) -> range(0, 5) 
• list(range(5)) -> [0,1,2,3,4]
• list(range(2,10,2)) -> [2,4,6,8]
• Dictonary
• product_price = {'book': 50, 'pen': 300, 'eraser': 10} 
• product_price.get('book') -> 50

2. Number Conversion in Python

• bin(28) -> 0b11100
• oct(28) -> 0o34 
• hex(28) ->  0x1c

3. Swap two numbers in Python

         a = 5

     b = 6

• Method #1:

            a, b = b, a

• Method #2

         a = a + b

      b = a - b

      a = a - b

4. "math" module in python

    import math

• math.sqrt(25) -> 5.0
• math.floor(2.5) -> 2.0
• math.ceil(2.5) -> 3.0
• math.pow(2, 3) -> 8.0
• math.pi -> 3.141592653589793
• math.e -> 2.718281828459045

5. How to import a module in python

• import math
• import math as m
• from math import sqrt, pow

6. How to take input from command line in python

from sys import argv

x = int(argv[1]) 

y = int(argv[2])

z = x + y

print(z)

7. Print below pattern in Python

str1 = "ABCD"

str2 = "PQR"

for i in range(4):

    print(str1[:i+1]+str2[i:])

8. Use else with for loop in python

• for loop must have 'break' statement in it to use the 'else'. 
• example: find the number in the list that is divisible by 2

                   digits = [7, 3, 5, 11]

        for digit in digits:

           if digit%2==0:

              print(digit)

              break;

        else:

           print('not found!')

9. Array in python

• Array is similar to list but must have elements of same datatype.

       from array import *

   # 'i' denotes the type of array i.e. integer

   digits = array('i', [1,2,4,5,7]) 

       # u denotes the unicode type array

   unico = array('u', ["a","k","s","h","a","y"])  

   #copying array

   digitcp = array(digits.typecode, [ a for a in digits]) 

   

   #print array with for loop

   for d in unico:

      print(d)

* These notes only meant to remind the basics of Python. These are not full notes.