How To Create NumPy Array In Python

Create Numpy Array From NumPy inbuilt functions

In this section we will learn to create numpy array using some numpy inbuilt functions. Numpy has various functions to create array but here we will see only following functions.

• zeros()
• ones()
• arange()
• linspace()
• logspace()

So let’s learn these numpy array methods to create numpy array.

zeros()

This method create an array which are filled with zeros. We just have to pass dimension of the array as argument to zeros() method, it will create the array according to passed argument.

So if you have to create an array in which all the values by default should be zero then zeros() function is used.

import numpy as np
zeros_array = np.zeros((2,2))
zeros_array

What we did?

• Here we have passed the dimension 2*2. It will create a numpy array of two rows and two columns.

Output

You can see in the output, a 2d numpy array has been created and filled with zeros. But in this array values are 0. which means they are float values. But if you want to work with integer then you have to specify data type. So let’s see how to do that.

import numpy as np
zeros_array = np.zeros((2,2), int)
zeros_array

Output

Ones()

This method create an array which are filled with zeros. We just have to pass dimension of the array as argument to ones() method, it will create the array according to passed argument.

So if you have to create an array in which all the values by default should be one then ones() function is used.

import numpy as np
ones_array = np.ones((3,3), int)
ones_array

• Here we have passed the dimension of array 3*3 to the ones() method. That will create an array of 3 rows and 3 columns filled with one.

Output

arange()

arange() function is frequently used to create  numpy array. To create array using this method we have to pass the range of the array as argument. It creates an array of passed range. Let’s understand it with an example. See the code below.

import numpy as np
arange_array = np.arange(15)
arange_array

• Here we have passed value of range 15. It will create an array with values ranging from 0 to 14.

Output

Let’s see the output.

NumPy create 1d array with particular range

You can see the values are from 0 to 14. But if we want to create an array of particular range, for ex. we have to create an array of ranging from 15to 30. Then how to do that. Let’s learn it with an example.

import numpy as np
arange_array = np.arange(15, 30)
arange_array

• Here we have passed the range of the array 15-30. It will create the array with values ranging from 15-29.
• Let’s see its output.

Output

NumPy create 1d array with particular sequence

Now if we have a case where we have to create an array of particular range with a sequence. For ex. we have to create an array of range 15-30 but also have to skip some values. Let’s understand it practically.

import numpy as np
arange_array = np.arange(15, 30, 2)
arange_array

• Here we have passed the skipping values 2. This will create an array of range 15-30 but skip two values.
• Lets’ see the output to understand properly.

Output

NumPy create 2d array with arange() method

import numpy as np
arange_array = np.arange(8).reshape(4,2)
arange_array

Output

NumPy create 3d array with arange() method

import numpy as np
arange_array = np.arange(8).reshape(2,2,2)
arange_array

Output

linspace()

It returns evenly spaced numbers over a specified interval. We have to pass three parameters to this method to create numpy array.

Run the following code.

import numpy as np
linspace_array = np.linspace(1,5,4)
linspace_array

• It will take the values from 1-5 and here retstep is 4 so it will break the values into 4 different parts.

logspace()

logspace() computes its start and end points as base**start and base**stop respectively. The base value can be specified, but is 10.0 by default.

import numpy as np
logspace_array = np.logspace(1,5,4)
logspace_array

Output

So guys its all about how to create numpy array in python tutorial. I hope you have found it helpful. If so then don’t forget to share it with your friends. And if you have any query then must drop your comment in comment section.