Essential Python Tips and Tricks for Programmers

We are going to cover some useful python tricks and tips that will come handy when you are writing program in competitive programming or for your company as they reduce the code and optimized execution.

Get n largest elements in a list using the module heapq

Example

import heapq

marks = [91, 67, 34, 56, 78, 99, 87, 23, 78, 66]
print("Marks = ",marks)

print("Largest =",heapq.nlargest(2, marks))

Output

Marks =  [91, 67, 34, 56, 78, 99, 87, 23, 78, 66]
Largest = [99, 91]

Get n smallest elements in a list using the module heapq

Example

import heapq

marks = [91, 67, 34, 56, 78, 99, 87, 23, 78, 66]
print("Marks = ",marks)

print("Smallest =",heapq.nsmallest(2, marks))

Output

Marks =  [91, 67, 34, 56, 78, 99, 87, 23, 78, 66]
Smallest = [23, 34]

Creating a single string from a list

Example

myList = ['Hello', 'World']
print(" ".join(myList))

Output

Hello World

Assign multiple variables in a single line

Example

a, b, c = 10, 20, 30
print(a, b, c)

Output

10 20 30

Loop through the elements in a list in a single line: List comprehensions

Example

myList = [5, 12, 15, 18, 24, 32, 55, 65]

res = [number for number in myList if number % 5 == 0]

print("Displaying numbers divisible by 5 = ",res)

Output

Displaying numbers divisible by 5 = [5, 15, 55, 65]

In-Place Swapping of two Numbers

Example

a, b = 50, 70
print("Before Swapping = ",a, b)

# swapping
a, b = b, a
print("After Swapping = ",a, b)

Output

Before Swapping = 50 70
After Swapping = 70 50

Reverse a string in a single line

Example

# Reverse a string
myStr = "This is it!!!"

print("String = ",myStr)
print("Reversed String = ",myStr[::-1])

Output

String =  This is it!!!
Reversed String =  !!!ti si sihT

Creating a dictionary from two related sequences

Example

# Creating a dictionary from two related sequences
s1 = ('Name', 'EmpId', 'Dept')
r1 = ('Jones', 767, 'Marketing')
print(dict (zip(s1, r1)))

Output

{'Name': 'Jones', 'EmpId': 767, 'Dept': 'Marketing'}

Inspect an object in python

Example

# Inspect an object in Python

myList =[1, 3, 4, 7, 9]
print(dir(myList))

Output

['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']