Initialize Array with Range of Numbers – NumPy

NumPy – Initialize Array with Range of Numbers

To initialise an array with a range of numbers in NumPy, you can use numpy.arange() function.

The syntax to call numpy.arange() function is

numpy.arange(start, stop, step)

where

• start [mandatory] is the starting of the range.
• stop [mandatory] is the ending of the range. stop is not inclusive in the returned array.
• step [optional] is the difference between adjacent numbers in the range.

The function returns a numpy array with elements starting from start, in steps of step value step, until stop.

Examples

1. Create 1D numpy array with numbers from 10 to 19

In the following program, we create one dimensional numpy array with a range of numbers from 10 upto 20(20 not included).

import numpy as np

arr = np.arange(10, 20)
print(arr)

Output

[10 11 12 13 14 15 16 17 18 19]

2. Create numpy array with numbers from 10 to 50 in steps of 5

In the following program, we create one dimensional numpy array with a range of numbers from 10 to 50 in steps of 5.

import numpy as np

arr = np.arange(10, 50, 5)
print(arr)

Output

[10 15 20 25 30 35 40 45]

3. Create 2D numpy array with a range of numbers

In the following program, we create a two dimensional array with a range of numbers starting from 1, with an array shape of (4, 5).

Since we need 4*5=20 elements to create an array of shape (4, 5), and start of the range is 1, ending of the range must be (4*5)+1.

import numpy as np

shape = (4, 5)
arr = np.arange(1, (4*5)+1).reshape(shape)
print(arr)

Output

[[ 1  2  3  4  5]
 [ 6  7  8  9 10]
 [11 12 13 14 15]
 [16 17 18 19 20]]

Summary

In this NumPy Tutorial, we learned how to create or initialise a numpy array with a range of numbers using numpy.arange() function.