This content originally appeared on flaviocopes.com and was authored by flaviocopes.com
Python provides 3 useful global functions we can use to work with collections: map(), filter() and reduce().
Tip: sometimes list comprehensions make more sense and are generally considered more pythonic
map() is used to run a function upon each item in an iterable item like a list, and create a new list with the same number of items, but the values of each item can be changed.
Example of map() being used to double each item in a list:
numbers = [1, 2, 3]
def double(a):
return a * 2
result = map(double, numbers)When the function is a one-liner, it’s common to use a lambda function:
numbers = [1, 2, 3]
double = lambda a : a * 2
result = map(double, numbers)and even inline it:
numbers = [1, 2, 3]
result = map(lambda a : a * 2, numbers)The original list is left untouched, and a new list with the updated values is returned by map().
The result is a map object, and you will need to cast it to a list to print its content:
print(list(result)) # [2, 4, 6]
This content originally appeared on flaviocopes.com and was authored by flaviocopes.com
flaviocopes.com | Sciencx (2021-02-26T05:00:00+00:00) How to use Python map(). Retrieved from https://www.scien.cx/2021/02/26/how-to-use-python-map/
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