--- title: Python Map Function published: true date: 2019-10-07 10:35:27 UTC tags: Python Tutorials,python,python map,python map example canonical_url: https://pythongeeks.net/python-tutorials/python-map-function/ --- Python `map` function is used to execute a function on all elements of an iterator. The function to execute will be passed to `map()` as a parameter. Through this blog post, we will understand `map()` function via many examples in coding. **A Quick Example:** ```python def newfunc(val): return val * 2 result = map(newfunc, [1, 2, 3, 4]) print(list(result)) # Result: [2, 4, 6, 8] ``` ![Python map function likes a short hand of a loop](https://i1.wp.com/pythongeeks.net/wp-content/uploads/2019/10/tower_bridge_sunset-wallpaper-1920x1080.jpg?resize=640%2C360&ssl=1)

Lambda function likes a short hand of a loop.
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### Definition and Usage In python, map function syntax is quite simple: ```python map(function, iterators) ``` - function: Required and will execute for items of iterators - iterators: Required. You can send many iterators. However, the function must have one parameter for each iterator. ### Python Map Examples #### **Example 1: How to use lambda function with map()** In the above example, we can make it shorter, cleaner with a lambda function. ```python result = map(lambda x: x * 2, [1, 2, 3, 4]) print(list(result)) # Result: [2, 4, 6, 8] ``` If you are new to Python, you should read this article for more detail of lambda function ([What is lambda function?](https://pythongeeks.net/python-tutorials/python-lambda-function/)) #### **Example 2: Passing multiple Iterators to map() function** Lambda function should have one parameter for each iterator. ```python iter1 = [1, 5, 7] iter2 = [9, 5, 3] result = map(lambda x, y: x + y, iter1, iter2) print(list(result)) # Result: [10, 10, 10] ``` #### **Example 3: Passing multiple Iterators with different size** Let's see what happen if we pass multiple iterators with different size. In python 2, we got an exception. Therefore, be aware of this case in your code. ```python iter1 = [1, 5, 7, 9, 8] iter2 = [9, 5, 3] result = map(lambda x, y: x + y, iter1, iter2) print(list(result)) """ Result: Traceback (most recent call last): File "main.py", line 6, in \ result = map(lambda x, y: x + y, iter2, iter1) File "main.py", line 6, in \ result = map(lambda x, y: x + y, iter2, iter1) TypeError: unsupported operand type(s) for +: 'NoneType' and 'int' """ ``` In python 3, we get a map object with the size of smallest iterator ```python iter1 = [1, 5, 7, 9, 8] iter2 = [9, 5, 3] result = map(lambda x, y: x + y, iter1, iter2) print(list(result)) # Result: [10, 10, 10] ``` ### References In this post, I provided some simple examples of the python map function. However, you can get more details from these links: - [Python Official Document](https://docs.python.org/3/library/functions.html#map) - [Python 2 Official Document](https://docs.python.org/2/library/functions.html#map) The post [Python Map Function](https://pythongeeks.net/python-tutorials/python-map-function/) appeared first on [Python Geeks](https://pythongeeks.net).

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Python Map Function

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