# 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.

## Python3

 `# 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))`

Output
```Sum =  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 :

## Python3

 `# 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)``set_result``=``list``(result)``print``(set_result)`

Output
```<map object at 0x7fdf95d2a6d8>
[1, 4, 9, 16]
```

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