# Sum 2D array in Python using map() function

Given a 2-D matrix, we need to find sum of all elements present in matrix ?

Examples:

Input : arr = [[1, 2, 3], [4, 5, 6], [2, 1, 2]] Output : Sum = 26

This problem can be solved easily using two for loops by iterating whole matrix but we can solve this problem quickly in python using map() function.

`# Function to calculate sum of all elements in matrix ` `# sum(arr) is a python inbuilt function which calculates ` `# sum of each element in a iterable ( array, list etc ). ` `# map(sum,arr) applies a given function to each item of ` `# an iterable and returns a list of the results. ` `def` `findSum(arr): ` ` ` ` ` `# inner map function applies inbuilt function ` ` ` `# sum on each row of matrix arr and returns ` ` ` `# list of sum of elements of each row ` ` ` `return` `sum` `(` `map` `(` `sum` `,arr)) ` ` ` `# Driver function ` `if` `__name__ ` `=` `=` `"__main__"` `: ` ` ` `arr ` `=` `[[` `1` `, ` `2` `, ` `3` `], [` `4` `, ` `5` `, ` `6` `], [` `2` `, ` `1` `, ` `2` `]] ` ` ` `print` `"Sum = "` `,findSum(arr) ` |

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Output:

26

**What does map() do?**

The map() function applies a given function to each item of an iterable(list, tuple etc.) and returns a list of the results. For example see given below example :

`# Python code to demonstrate working of map() ` ` ` `# Function to calculate square of any number ` `def` `calculateSquare(n): ` ` ` `return` `n` `*` `n ` ` ` `# numbers is a list of elements ` `numbers ` `=` `[` `1` `, ` `2` `, ` `3` `, ` `4` `] ` ` ` `# Here map function is mapping calculateSquare ` `# function to each element of numbers list. ` `# It is similar to pass each element of numbers ` `# list one by one into calculateSquare function ` `# and store result in another list ` `result ` `=` `map` `(calculateSquare, numbers) ` ` ` `# resultant output will be [1,4,9,16] ` `print` `result ` |

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Output :

[1, 4, 9, 16]

This article is contributed by **Shashank Mishra (Gullu)**. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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