NumPy Tutorial · NumPy Tutorial

NumPy Array Slicing

Learn all about NumPy Array Slicing in this comprehensive tutorial.

5 min read intermediate

•Slicing in python means taking elements from one given index to another given index.
•Use the minus operator to refer to an index from the end:
•Use the step value to determine the step of the slicing:

Slicing arrays

Slicing in python means taking elements from one given index to another given index.

We pass slice instead of index like this: [start:end].

We can also define the step, like this: [start:end:step].

If we don't pass start its considered 0

If we don't pass end its considered length of array in that dimension

If we don't pass step its considered 1

python

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

Note: Note: The result includes the start index, but excludes the end index.

python

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

python

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

Use the minus operator to refer to an index from the end:

python

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

Use the step value to determine the step of the slicing:

python

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

python

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

python

import numpy as nparr = np.array([[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]])
print(arr[1, 1:4])

Note: Note: Remember that second element has index 1.

python

import numpy as nparr = np.array([[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]])
print(arr[0:2, 2])

python

import numpy as nparr = np.array([[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]])
print(arr[0:2, 1:4])

2 questions

Which of the following is true about NumPy Array Slicing?

It is strictly typedIt is evaluated at runtimeIt requires explicit memory managementIt is deprecated

What is the most common pitfall when working with NumPy Array Slicing?

SyntaxErrorIndentationErrorNameErrorTypeError

Answer all questions to submit.