Python: Difference between filter(function, sequence) and map(function, sequence)

Question

I\'m reading through the Python documentation to really get in depth with the Python language and came across the filter and map functions. I have used filter before, but never

Answer 1

Filter--Returns the true value's position

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var_list = [10,20,0,1]

var_b = list(filter(lambda var_a : var_a*2,var_list))

print("Values are",var_b)

Output

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Values are [10, 20, 1]

Map--Returns the actual result

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var_list = [10,20,0,1]

var_b = list(map(lambda var_a : var_a*2,var_list))

print("Values are",var_b)

Output

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Values are [20, 40, 0, 2]

Reduce--Take the first 2 items in the list,then calls function, In next function call,the result of previous call will be 1st argument and 3rd item in list will be 2nd argument

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from functools import *

var_list = [10,20,0,1]

var_b = list(map(lambda var_a : var_a*2,var_list))

print("Values of var_b ",var_b)

var_c = reduce(lambda a,b:a*2,var_b)

print("Values of var_c",var_c)

Output

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Values of var_b [20, 40, 0, 2]

Values of var_c 160