The Map, Filter, and Reduce Functions in Python

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This video introduces the map, filter, and reduce functions in Python.

[MrSimospirit]

you are amazing thank you for sharing.

[haneulkim]

Thanks for great video! Why would one use map function over list comprehension. What are the difference?

[neofit]

I ask for a video about the decorator and the meta class ))

[songokussjcz]

Hi, I like your videos and the way you present the subject. But today I think all functions are wrong to use in modern Python.
With numbers = [1, 2, 3, 4, 5]

MAP
List comprehension does the same thing, maybe faster and is more readable.
>>> def square(x):
>>> return x**2
>>> list(map(square, numbers)) # MAP
>>> [1, 4, 9, 16, 25]
>>> [square(x) for x in numbers] # List Comprehension
>>> [1, 4, 9, 16, 25]

>>> list(map(lambda x: x**2, numbers)) # MAP with lambda
>>> [1, 4, 9, 16, 25]
>>> [x**2 for x in numbers] # List Comprehension
>>> [1, 4, 9, 16, 25]
Again... More readable

FILTER
List comprehension again more readable for human eye
>>> list(filter(lambda x: x > 3, numbers)) # FILTER
>>> [4, 5]
>>> [x for x in numbers if x > 3] # List Comprehension
>>> [4, 5]

REDUCE
List comprehension can't be used but as said in one Stack Overflow:
"Removed reduce(). Use functools.reduce() if you really need it; however, 99 percent of the time an explicit for loop is more readable."
It's only for Python2, which is dying breed... If you use it in Python3, it does not exist!
>>> result = 0
>>> for num in numbers:
>>> result += num
>>> result
>>> 15

These are my 2 cents for this subject.
If you think I'm wrong I'll be happy to see in your next video some useful cases where List Comprehension is worse choice.

[sromanski]

It's interesting that you have to import the reduce function and not map or filter.