# numpy.sum() in Python

• Last Updated : 07 Nov, 2022

numpy.sum(arr, axis, dtype, out) : This function returns the sum of array elements over the specified axis.

Parameters :
arr : input array.
axis : axis along which we want to calculate the sum value. Otherwise, it will consider arr to be flattened(works on all the axis). axis = 0 means along the column and axis = 1 means working along the row.
out : Different array in which we want to place the result. The array must have same dimensions as expected output. Default is None.
initial : [scalar, optional] Starting value of the sum.
Return : Sum of the array elements (a scalar value if axis is none) or array with sum values along the specified axis.

Code #1:

## Python3

 `# Python Program illustrating``# numpy.sum() method``import` `numpy as np``     ` `# 1D array``arr ``=` `[``20``, ``2``, .``2``, ``10``, ``4``] `` ` `print``("\nSum of arr : ", np.``sum``(arr))`` ` `print``("``Sum` `of arr(uint8) : ", np.``sum``(arr, dtype ``=` `np.uint8))``print``("``Sum` `of arr(float32) : ", np.``sum``(arr, dtype ``=` `np.float32))`` ` `print` `("\nIs np.``sum``(arr).dtype ``=``=` `np.uint : ",``       ``np.``sum``(arr).dtype ``=``=` `np.uint)` `print` `("Is np.``sum``(arr).dtype ``=``=` `np.``float` `: ",``       ``np.``sum``(arr).dtype ``=``=` `np.``float``)`

Output:

```Sum of arr :  36.2
Sum of arr(uint8) :  36
Sum of arr(float32) :  36.2

Is np.sum(arr).dtype == np.uint :  False
Is np.sum(arr).dtype == np.float :  True```

Code #2:

## Python3

 `# Python Program illustrating``# numpy.sum() method``import` `numpy as np``     ` `# 2D array``arr ``=` `[[``14``, ``17``, ``12``, ``33``, ``44``],  ``       ``[``15``, ``6``, ``27``, ``8``, ``19``], ``       ``[``23``, ``2``, ``54``, ``1``, ``4``,]] `` ` `print``("\nSum of arr : ", np.``sum``(arr))`` ` `print``("``Sum` `of arr(uint8) : ", np.``sum``(arr, dtype ``=` `np.uint8))``print``("``Sum` `of arr(float32) : ", np.``sum``(arr, dtype ``=` `np.float32))`` ` `print` `("\nIs np.``sum``(arr).dtype ``=``=` `np.uint : ",``                 ``np.``sum``(arr).dtype ``=``=` `np.uint)` `print` `("Is np.``sum``(arr).dtype ``=``=` `np.``float` `: ",``              ``np.``sum``(arr).dtype ``=``=` `np.``float``)`

Output:

```Sum of arr :  279
Sum of arr(uint8) :  23
Sum of arr(float32) :  279.0

Is np.sum(arr).dtype == np.uint :  False
Is np.sum(arr).dtype == np.float :  False```

Code #3:

## Python3

 `# Python Program illustrating``# numpy.sum() method``     ` `import` `numpy as np``     ` `# 2D array ``arr ``=` `[[``14``, ``17``, ``12``, ``33``, ``44``],  ``       ``[``15``, ``6``, ``27``, ``8``, ``19``], ``       ``[``23``, ``2``, ``54``, ``1``, ``4``,]] `` ` `print``("\nSum of arr : ", np.``sum``(arr))``print``("``Sum` `of arr(axis ``=` `0``) : ", np.``sum``(arr, axis ``=` `0``))``print``("``Sum` `of arr(axis ``=` `1``) : ", np.``sum``(arr, axis ``=` `1``))` `print``("\nSum of arr (keepdimension ``is` `True``): \n",``      ``np.``sum``(arr, axis ``=` `1``, keepdims ``=` `True``))`

Output:

```Sum of arr :  279
Sum of arr(axis = 0) :  [52 25 93 42 67]
Sum of arr(axis = 1) :  [120  75  84]

Sum of arr (keepdimension is True):
[[120]
[ 75]
[ 84]]```

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