Splitting arrays in NumPy

Hello guys. Welcome to another exciting session on this platform. If you are new, please do check out our previous articles on NumPy and other programming languages of choice. Also check out YouTube channel to get the full video tutorials.

In the previous article, we saw how we could join two arrays in NumPy, but now we are going to see how to split an array into multiple sub-arrays. NumPy has built-in function called

array_split which is used to spit array. With this function, we can have as many arrays as we want.

Example 

import numpy as np
arr = np.array(['a', 'b', 'c', 'd'])
newarr = np.array_split(arr, 2)
print(newarr)

We pass the array we want to split to the function while specifying the number to which we want spilt the array. After this the compiler will execute the program.

OUTPUT

In a case where the arrays have less elements than required elements, the compiler arranges the elements at end. 

Example

import numpy as np
arr = np.array(['a', 'b', 'c', 'd', 'e'])
newarr = np.array_split(arr, 3)
print(newarr)

OUTPUT

Splitting 2-D Arrays

We are still going to apply the same function

Example 

import numpy as np
arr = np.array([['a', 'b'], ['c', 'd'], ['e', 'f'], ['g', 'h']])
newarr = np.array_split(arr,2)
print(newarr)

The compiler splits the input array into 3 sub-different arrays given to it by array.split. 

2-D arrays 

OUTPUT

We can spit arrays vertically, horizontal or depth-wise. We do this using any of these functions below: hsplit(), vsplit() and dsplit(). These functions are found in NumPy The position is always specified after the spilt has occur.

Vertically spiting: we are going to use the function vsplit(). This functions splits array row-wise. After the spitting has occur, the resulting arrays is arranged in order row order.

Example

import numpy as np
a = np.arange(9).reshape(3, 3)
print("The array {} gets splitted \
vertically to form {} ".format(a, np.vsplit(a, 3)))

OUTPUT

Horizontal spiting: We are going use the hsplit(). The functions spits array column wise that is horizontally. After the splitting occurs, the resulting array is arranged in column order.

Example

import numpy as np
a = np.arange(9).reshape(3, 3)
print("The array {} gets splitted \
horizontally to form {} ".format(a, np.hsplit(a, 3)))

The array is passed to the spit function. After the spitting has occur, the position (orientation of the array) is then specified for the compiler to execute the program.

OUTPUT

Depth wise: we are going to spilt an array into sub-arrays along depth. 

import numpy as np
a = np.arange(9).reshape(3, 3)
print("The array {} gets splitted \
depth-wise to form {} ".format(a, np.hsplit(a, 3)))

OUTPUT

We have come to the end of this session. I hope you found this guide useful. If so, do share it with others who are willing to learn NumPy and Python. If you have any questions related to this article, feel free to ask us in the comments section.