Python - Mapping Functions over Iterables: map

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Introduction

You can apply an operation to lists and other sequences for each item and collect the results.

The following code shows how to update all the counters in a list can be done easily with a for loop:

Demo

counters = [1, 2, 3, 4] 
updated = [] #  ww  w.ja va 2  s.  c  o m
for x in counters: 
    updated.append(x + 10)                 # Add 10 to each item 

print( updated )

Result

Python provides built-ins that do most of the work.

The map function applies a function to each item in an iterable object and returns a list containing all the function call results.

For example:

Demo

counters = [1, 2, 3, 4] 
def inc(x): return x + 10                  # Function to be run 
# from w  w w .ja  v  a 2s  .  c  o  m
d=list(map(inc, counters))                   # Collect results 
print( d )

Result

Here, we map inc method on each list item and collects all the return values into a new list.

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