Difference between Map and Filter functions in Python

In Python, map and filter functions look similar and establishing the difference between the two might be sometime confusing.

In this post, I would like to highlight the basic difference between the two functions with clear examples.

While Maps takes a normal function, Filter takes Boolean functions. As a matter of fact, filter are maps with conditional logic, a Boolean logic.

Let's put this into perspective with examples.

nums = [11, 22, 33, 44, 55]

Below is an example using map

map = list(map(lambda x: x**2, nums))
print(map)

[121, 484, 1936, 3025]
Below is an example using filter

filter = list(filter(lambda x: x%2==0, nums))
print(filter)

[22, 44]
As you can see, the two examples modified the nums list. But while Map modifies the list with a normal logic that produces another list, Filter modifies the list with conditional logic that filters out some elements--those that do not meet the conditions of the Boolean logic---from the nums list.

I hope this brings a clearer picture into the concept of map and filter in python.

Thanks