NumPy arange()

import numpy as np

# create an array with elements from 5 to 10
array1 = np.arange(5, 10)

print(array1)

# Output: [5 6 7 8 9]

arange() Syntax

The syntax of arange() is:

numpy.arange(start = 0, stop, step = 1, dtype = None)

arange() Argument

The arange() method takes the following arguments:

• start(optional)- the start value of the interval range (int or real)
• stop- the end value of the interval range (exclusive) (int or real)
• step(optional)- step size of the interval (int or real)
• dtype(optional)- type of output array(dtype)

arange() Return Value

The arange() method returns an array of evenly spaced values.

Example 1: Create a 1-D Array Using arange

import numpy as np

# create an array with first five elements
array1 = np.arange(5)

# create an array with elements from 5 to 10(exclusive)
array2 = np.arange(5, 10)

# create an array with elements from 5 to 15 with stepsize 2
array3 = np.arange(5, 15, 2)

print(array1)
print(array2)
print(array3)

Output

[0 1 2 3 4]
[5 6 7 8 9]
[ 5  7  9 11 13]

Example 2: Create a Floating Point 1-D Array Using arange

import numpy as np

# create an array with elements from 0 to 1 with stepsize 0.2
array1 = np.arange(0, 1, 0.2)

print(array1)

Output

[0.  0.2 0.4 0.6 0.8]

Example 3: Passing Negative Valued Arguments in arange

import numpy as np

# create an array with elements from -5 to 5 with step size 2
array1 = np.arange(-5, 5, 2)

# create an array with elements from -15 to -5 with step size 2
array2 = np.arange(-15, -5, 2)

# create an array with elements from 15 to 5 with step size -2
array3 = np.arange(15, 5, -2)

print(array1) 
print(array2) 
print(array3) 

Output

[-5 -3 -1  1  3]
[-15 -13 -11  -9  -7]
[15 13 11  9  7]

Key Differences Between arange and linspace

Both np.arange() and np.linspace() are NumPy functions used to generate numerical sequences, but they have some differences in their behavior.

• arange() generates a sequence of values from start to stop with a given step size whereas linspace generates a sequence of num evenly spaced values from start to stop.
• arange() excludes stop value whereas linspace includes stop value unless specified otherwise by endpoint = False

Let us look at an example.

import numpy as np

# elements between 10 and 40 with stepsize 4
array1 = np.arange(10, 50 ,4)

# generate 4 elements between 10 and 40 
array2 = np.linspace(10, 50 ,4)

print('Using arange:',array1)  # doesn't include 50
print('Using linspace:',array2)  # includes 50

Output

Using arange: [10 14 18 22 26 30 34 38 42 46]
Using linspace: [10.         23.33333333 36.66666667 50.        ]