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.

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

Python Program

import numpy as np

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

Output

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

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

Python Program

import numpy as np

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

Output

[10 15 20 25 30 35 40 45]

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.

Python Program

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]]

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