Day 30 - Learn the concept of comprehension,lambda,map,filter,reduce via simple examples

 # -*- coding: utf-8 -*-

"""

Created on Tue Sep  8 11:20:22 2020

@author: Rakesh.Ranjan

"""

def square(x):  

  return x**2  

def even(x):  

  return x%2 == 0

 

numbers = [1,2,3,4] 

#Comprehension

#1. the expression inside the brackets first starts with the operation/output that you desire, and then loops and conditionals occur in the same order of the regular code. 

lc_square = [numbers[i]**2 for i in range(len(numbers))]

print('Comprehension example:',lc_square)

#lambda 

#lambda input parameter(s):operation/output 

countries = ['India','Pakistan','Bhutan','Nepal','Bangladesh']

func_lambda = lambda x: x.lower()

print('lambda example:',func_lambda('India'))

#A. Map 

#map(function,iterable object) 

#1. The function here can be a lambda function or a function object. 

#2. The iterable object can be a string, list, tuple, set or dictionary. 

lm_map = map(square, numbers)  

print('map example:',list(lm_map)) 

#B. Filter

#filter(function,iterable object) 

#1. The function object passed to the filter function should always return a boolean value. 

#2. The iterable object can be a string, list, tuple, set or dictionary. 

divby2 = lambda x : x % 2 == 0

even_filter = filter(divby2, numbers)  

even_map = map(even, numbers) 

 

print('map example:',list(even_map),' filer example:', list(even_filter)) 

#C. Reduce

#reduce(function,iterable object)

#1. The function object passed to the reduce function decides what expression is passed to the iterable object.

#2. The iterable object can be a string, list, tuple, set or dictionary.

#3. Also, reduce function produces a single output.

from functools import reduce 

fact = lambda x,y : x * y 

lf_filter = reduce(fact,numbers)

print('Reduce example:',lf_filter)

Output:

#RR #Day30 #Python #Function #comprehension  #lambda #map #filter #reduce #HappyLearning #WeLearnEveryday