python snippets

accessing-index-and-value-at-same-time.py

## enumerate() inbuilt function lets you access index and value at the same time within a or loop
arr = [2,4,6,3,8,10]

for index,value in enumerate(arr):
  print(f"At Index {index} The Value Is -> {value}")

'''Output
At Index 0 The Value Is -> 2
At Index 1 The Value Is -> 4
At Index 2 The Value Is -> 6
At Index 3 The Value Is -> 3
At Index 4 The Value Is -> 8
At Index 5 The Value Is -> 10
'''

add-elements-of-two-lists.py

## Let’s say you have two lists and you want to merge them into one single list by adding their elements. It can be useful in some scenarios like

maths = [59, 64, 75, 86]
physics = [78, 98, 56, 56] 

# Brute Force Method
list1 = [
  maths[0]+physics[0],
  maths[1]+physics[1],
  maths[2]+physics[2],
  maths[3]+physics[3]
]


# List Comprehension
list1 = [x + y for x,y in zip(maths,physics)]

# Using Maps
import operator 
all_devices = list(map(operator.add, maths, physics))

# Using Numpy Library
import numpy as np
list1 = np.add(maths,physics)

'''Output
[137 162 131 142]
'''

calc-without-ifelse.py

## This code snippet shows how simply you can write a calculator without using any if-else conditions.

import operator

action = {
  "+" : operator.add,
  "-" : operator.sub,
  "/" : operator.truediv,
  "*" : operator.mul,
  "**" : pow
}

print(action['*'](5, 5))    # 25

calculate-time-of-shell.py

## It becomes important sometimes to know the execution time of the shell or code block to get a better algorithm with minimum time spent.

# METHOD 1
import datetime
start = datetime.datetime.now()
"""
CODE
"""
print(datetime.datetime.now()-start)

# METHOD 2
import time
start_time = time.time()
main()
print(f"Total Time To Execute The Code is {(time.time() - start_time)}" )

# METHOD 3
import timeit
code = '''
## Code snippet whose execution time is to be measured
[2,6,3,6,7,1,5,72,1].sort()
'''
print(timeit.timeit(stmy = code,number = 1000))

chained-func-call.py

## You can call multiple functions on one line in python.

def add(a,b):
  return a+b

def sub(a,b):
  return a-b

a,b = 9,6
print((sub if a > b else add)(a, b))

check-for-anagram.py

## An anagram is a word that is formed by rearranging the letters of a different word, using all the original letters exactly once.
def check_anagram(first_word, second_word):
  return sorted(first_word) == sorted(second_word)
  
print(check_anagram("silent", "listen"))   # True
print(check_anagram("ginger", "danger"))   # False

check-if-file-exists.py

# Brute force Method
import os.path
from os import path

def check_for_file():
	print("File exists: ",path.exists("data.txt"))

if __name__=="__main__":
   check_for_file()
    
'''
File exists:  False
'''

check-substring-in-string-list.py

##  Check whether a string contains a substring.

addresses = [
  "12/45 Elm street",
  '34/56 Clark street',
  '56,77 maple street',
  '17/45 Elm street'

]
street = 'Elm street'
for i in addresses:
  if street in i:
    print(i)

'''output
12/45 Elm street
17/45 Elm street
'''

convert-two-list-to-dict.py

## The following method can be used to convert two lists into a dictionary.

convert-two-lists-to-dict.py

## The following method can be used to convert two lists into a dictionary.

list1 = ['karl','lary','keera']
list2 = [28934,28935,28936]

# Method 1: zip()
dictt0 = dict(zip(list1,list2))

# Method 2: dictionary comprehension
dictt1 = {key:value for key,value in zip(list1,list2)}

# Method 3: Using a For Loop (Not Recommended)
tuples = zip(list1, list2) 
dictt2 = {} 
for key, value in tuples: 
  if key in dictt2: 
    pass
  else: 
    dictt2[key] = value
print(dictt0, dictt1, dictt2, sep = "\n")

error-handling.py

## Like Java and C++, python also offers a way to handle exceptions using try, except, and finally block.

# Example 1
try:  
    a = int(input("Enter a:"))    
    b = int(input("Enter b:"))    
    c = a/b  
    print(c)
except:  
    print("Can't divide with zero") 
    
# Example 2
try:    
    #this will throw an exception if the file doesn't exist.     
    fileptr = open("file.txt","r")    
except IOError:    
    print("File not found")    
else:    
    print("The file opened successfully")    
    fileptr.close()  

# Example 3
try:
  fptr = open("data.txt",'r')
  try:
    fptr.write("Hello World!")
  finally:
    fptr.close()
    print("File Closed")
except:
  print("Error")
  

format-string.py

## The most important part of a code is the input, logic, and output. All three parts require some sort of formatting while writing the code for better and easy-to-read outputs. 

name = "Abhay"
age = 21

## METHOD 1: Concatenation
print("My name is "+name+", and I am "+str(age)+ " years old.")

## METHOD 2: F-strings (Python 3+)
print(f"My name is {name}, and I am {age} years old")

## METHOD 3: Join
print(''.join(["My name is ", name, ", and I am ", str(age), " years old"]))

## METHOD 4: modulus operator
print("My name is %s, and I am %d years old." % (name, age))

## METHOD 5: format(Python 2 and 3)
print("My name is {}, and I am {} years old".format(name, age))

merge-two-dicts.py

## This will come in handy when you are dealing with databases and JSON files and need to merge multiple data from different files or tables into a common file. 

basic_information = {"name":['karl','Lary'],"mobile":["0134567894","0123456789"]}
academic_information = {"grade":["A","B"]}
details = dict() ## Combines Dict

## Dictionary Comprehension Method
details = {key: value for data in (basic_information, academic_information) for key,value in data.items()}
print(details)

## Dictionary unpacking
details = {**basic_information ,**academic_information}
print(details)

## Copy and Update Method
details = basic_information.copy()
details.update(academic_information)
print(details)

sort-dict-list.py

## When you have a list of dictionaries, you might want to organize them in sorted order with the help of a key.

dict1 = [
    {"Name":"Karl",
     "Age":25},
     {"Name":"Lary",
     "Age":39},
     {"Name":"Nina",
     "Age":35}
]

## Using sort()
dict1.sort(key=lambda item: item.get("Age"))

# List sorting using itemgetter
from operator import itemgetter
f = itemgetter('Name')
dict1.sort(key=f)


# Iterable sorted function
dict1 = sorted(dict1, key=lambda item: item.get("Age"))

'''Output
[{'Age': 25, 'Name': 'Karl'},
 {'Age': 35, 'Name': 'Nina'},
 {'Age': 39, 'Name': 'Lary'}]
'''

sort-string-list.py

## This can be useful when you have a list containing the names of students and you want to sort all the names.

# Method 1: sort()
list1.sort()

# Method 2: sorted()
sorted_list = sorted(list1)

# Method 3: Brute Force Method 
size = len(list1)
for i in range(size): 
  for j in range(size): 
    if list1[i] < list1[j]: 
       temp = list1[i] 
       list1[i] = list1[j] 
       list1[j] = temp
print(list1)

space-separated-input.py

## Taking Two Integers as input at once
a,b = map(int,input().split())
print("a:",a)
print("b:",b)

## Taking a List as input
arr = list(map(int,input().split()))
print("Input List:",arr)

square-numbers-in-range.py

## In this snippet, we take the help of inbuilt function itertools to find the square of every integer in a given range.

# METHOD 1
from itertools import repeat

n = 5
squares = list(map(pow, range(1, n+1), repeat(2)))
print(squares)

# METHOD 2
n = 6
squares = [i**2 for i in range(1,n+1)]
print(squares)


"""Output
  [1, 4, 9, 16, 25]
"""