# Flatten A list of NumPy arrays

• Last Updated : 16 Sep, 2021

In this article, we will see how we can flatten a list of numpy arrays. NumPy is a library for the Python programming language, adding support for large, multi-dimensional arrays and matrices, along with a large collection of high-level mathematical functions to operate on these arrays.

Flatten a list of NumPy array means to combine the multiple dimensional NumPy arrays into a single array or list, below is the example

List of numpy array :
[array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]]),
array([[ 0.00353654]])]

Flatten numpy array :
array([ 0.00353654, 0.00353654, 0.00353654, 0.00353654, 0.00353654,
0.00353654, 0.00353654, 0.00353654, 0.00353654, 0.00353654,
0.00353654, 0.00353654, 0.00353654])

Method 1
Using numpy’s concatenate method

## Python3

 `# importing numpy as np``import` `numpy as np` `# list of numpy array``list_array ``=` `[np.array([[``1``]]),``               ``np.array([[``2``]]),``               ``np.array([[``3``]]),``               ``np.array([[``4``]]),``               ``np.array([[``5``]]),``               ``np.array([[``6``]]),``               ``np.array([[``7``]]),``               ``np.array([[``8``]]),``               ``np.array([[``9``]]),``               ``np.array([[``10``]]),``               ``np.array([[``11``]]),``               ``np.array([[``12``]]),``               ``np.array([[``13``]]),``               ``np.array([[``14``]]),``               ``np.array([[``15``]]),``               ``np.array([[``16``]])]` `# concatenating all the numpy array``flatten ``=` `np.concatenate(list_array)` `# printing the ravel flatten array``print``(flatten.ravel())`

Output :

`[ 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16]`

Method 2
Using numpy’s flatten method

## Python3

 `# importing numpy as np``import` `numpy as np` `# list of numpy array``list_array ``=` `[np.array([[``1``]]),``               ``np.array([[``2``]]),``               ``np.array([[``3``]]),``               ``np.array([[``4``]]),``               ``np.array([[``5``]]),``               ``np.array([[``6``]]),``               ``np.array([[``7``]]),``               ``np.array([[``8``]]),``               ``np.array([[``9``]]),``               ``np.array([[``10``]]),``               ``np.array([[``11``]]),``               ``np.array([[``12``]]),``               ``np.array([[``13``]]),``               ``np.array([[``14``]]),``               ``np.array([[``15``]]),``               ``np.array([[``16``]])]` `# flatten the numpy array``flatten ``=` `np.array(list_array).flatten()` `# printing the flatten array``print``(flatten)`

Output :

`[ 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16]`

Method 3
Using numpy’s ravel method

## Python3

 `# importing numpy as np``import` `numpy as np` `# list of numpy array``list_array ``=` `[np.array([[``1``]]),``               ``np.array([[``2``]]),``               ``np.array([[``3``]]),``               ``np.array([[``4``]]),``               ``np.array([[``5``]]),``               ``np.array([[``6``]]),``               ``np.array([[``7``]]),``               ``np.array([[``8``]]),``               ``np.array([[``9``]]),``               ``np.array([[``10``]]),``               ``np.array([[``11``]]),``               ``np.array([[``12``]]),``               ``np.array([[``13``]]),``               ``np.array([[``14``]]),``               ``np.array([[``15``]]),``               ``np.array([[``16``]])]` `# flatten the numpy array using ravel method``flatten ``=` `np.array(list_array).ravel()` `# printing the flatten array``print``(flatten)`

Output :

`[ 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16]`

Method 4
Using numpy’s reshape method

## Python3

 `# importing numpy as np``import` `numpy as np` `# list of numpy array``list_array ``=` `[np.array([[``1``]]),``               ``np.array([[``2``]]),``               ``np.array([[``3``]]),``               ``np.array([[``4``]]),``               ``np.array([[``5``]]),``               ``np.array([[``6``]]),``               ``np.array([[``7``]]),``               ``np.array([[``8``]]),``               ``np.array([[``9``]]),``               ``np.array([[``10``]]),``               ``np.array([[``11``]]),``               ``np.array([[``12``]]),``               ``np.array([[``13``]]),``               ``np.array([[``14``]]),``               ``np.array([[``15``]]),``               ``np.array([[``16``]])]` `# flatten the numpy array using reshape method``flatten ``=` `np.array(list_array).reshape(``-``1``)` `# printing the flatten array``print``(flatten)`

Output :

`[ 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16]`

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