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])

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