np.split() for dividing arrays in NumPy - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of np.split() with equal splits

What is the output of the following code?

import numpy as np
arr = np.array([10, 20, 30, 40, 50, 60])
splits = np.split(arr, 3)
print(splits)

NumPy

import numpy as np
arr = np.array([10, 20, 30, 40, 50, 60])
splits = np.split(arr, 3)
print(splits)

A [array([10, 20, 30, 40]), array([50, 60])]

B [array([10, 20, 30]), array([40, 50, 60])]

C [array([10]), array([20, 30, 40]), array([50, 60])]

D [array([10, 20]), array([30, 40]), array([50, 60])]

💡 Hint

np.split divides the array into equal parts if possible.

np.split(arr, 3) splits the array into 3 equal parts. Since arr has 6 elements, each part has 2 elements.

❓ Predict Output

intermediate

Output of np.split() with indices_or_sections as list

What is the output of this code?

import numpy as np
arr = np.array([1, 2, 3, 4, 5, 6, 7])
splits = np.split(arr, [2, 5])
print(splits)

NumPy

import numpy as np
arr = np.array([1, 2, 3, 4, 5, 6, 7])
splits = np.split(arr, [2, 5])
print(splits)

A [array([1, 2]), array([3, 4, 5]), array([6, 7])]

B [array([1, 2, 3]), array([4, 5]), array([6, 7])]

C [array([1, 2]), array([3, 4]), array([5, 6, 7])]

D [array([1]), array([2, 3, 4]), array([5, 6, 7])]

💡 Hint

The list [2, 5] means split before index 2 and before index 5.

np.split(arr, [2, 5]) splits arr into three parts: elements before index 2, elements from 2 to 4, and elements from 5 onwards.

❓ data_output

advanced

Number of sub-arrays after splitting

How many sub-arrays are created by this code?

import numpy as np
arr = np.arange(12)
splits = np.split(arr, [3, 7, 10])
print(len(splits))

NumPy

import numpy as np
arr = np.arange(12)
splits = np.split(arr, [3, 7, 10])
print(len(splits))

A 4

B 3

C 5

D 6

💡 Hint

Number of sub-arrays is one more than the number of split indices.

With split indices [3,7,10], np.split creates 4 sub-arrays.

🔧 Debug

advanced

Error raised by np.split with invalid split

What error does this code raise?

import numpy as np
arr = np.array([1, 2, 3, 4])
splits = np.split(arr, 3)

NumPy

import numpy as np
arr = np.array([1, 2, 3, 4])
splits = np.split(arr, 3)

A IndexError: index out of bounds

B ValueError: array split does not result in an equal division

C TypeError: indices_or_sections must be an integer or 1-D array

D No error, splits into 3 parts

💡 Hint

The array length is not divisible by 3.

np.split requires equal division if given an integer. Here 4 elements cannot be split equally into 3 parts.

🚀 Application

expert

Using np.split to divide a 2D array by columns

Given a 2D array with shape (4, 6), which option correctly splits it into three arrays each with 2 columns?

import numpy as np
arr = np.arange(24).reshape(4, 6)
splits = np.split(arr, ?, axis=1)
print([s.shape for s in splits])

NumPy

import numpy as np
arr = np.arange(24).reshape(4, 6)
splits = np.split(arr, ?, axis=1)
print([s.shape for s in splits])

A [0, 2, 4]

B 3

C [2, 4]

D [1, 3, 5]

💡 Hint

Split indices mark column positions where to split.

Splitting at columns 2 and 4 divides 6 columns into three parts with 2 columns each.