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Nudge Notes - Python Language Basics

Python 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
A P Q R A B Q R A B C R A B C D


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.
Python array typecode table


       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.

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