Python map() Function
Python Built-in FunctionsDescription
map()Maps the specified sequence according to the provided function.
The first parameter function calls the function with each element in the parameter sequence, returning a new list containing the return value of each function call.
Syntax
map() function syntax:
map(function, iterable, ...)
Parameters
- function -- Function
- iterable -- One or more sequences
Return Value
Python 2.x returns a list.
Python 3.x returns an iterator.
Examples
The following examples demonstrate how to use map():
Python2.x Examples
>>> def square(x) : # Calculate square numbers
... return x ** 2
...
>>> map(square, [1,2,3,4,5]) # Calculate the square of each element in the list
[1, 4, 9, 16, 25]
>>> map(lambda x: x ** 2, [1, 2, 3, 4, 5]) # Use lambda anonymous function
[1, 4, 9, 16, 25]
# Two lists are provided, adding the data at the same positions
>>> map(lambda x, y: x + y, [1, 3, 5, 7, 9], [2, 4, 6, 8, 10])
[3, 7, 11, 15, 19]
... return x ** 2
...
>>> map(square, [1,2,3,4,5]) # Calculate the square of each element in the list
[1, 4, 9, 16, 25]
>>> map(lambda x: x ** 2, [1, 2, 3, 4, 5]) # Use lambda anonymous function
[1, 4, 9, 16, 25]
# Two lists are provided, adding the data at the same positions
>>> map(lambda x, y: x + y, [1, 3, 5, 7, 9], [2, 4, 6, 8, 10])
[3, 7, 11, 15, 19]
Python3.x Examples
>>> def square(x) : # Calculate square numbers
... return x ** 2
...
>>> map(square, [1,2,3,4,5]) # Calculate the square of each element in the list
<map object at 0x100d3d550> # Returns an iterator
>>> list(map(square, [1,2,3,4,5])) # Use list() to convert to a list
[1, 4, 9, 16, 25]
>>> list(map(lambda x: x ** 2, [1, 2, 3, 4, 5])) # Use lambda anonymous function
[1, 4, 9, 16, 25]
>>>
... return x ** 2
...
>>> map(square, [1,2,3,4,5]) # Calculate the square of each element in the list
<map object at 0x100d3d550> # Returns an iterator
>>> list(map(square, [1,2,3,4,5])) # Use list() to convert to a list
[1, 4, 9, 16, 25]
>>> list(map(lambda x: x ** 2, [1, 2, 3, 4, 5])) # Use lambda anonymous function
[1, 4, 9, 16, 25]
>>>