# NumPy Create an Empty Array or Matrix: A Beginner Guide – NumPy Tutorial

By | May 16, 2020

Empty array and matrix is an important data in numpy. In this tutorial, we will introduce how to create them using some simple examples.

## Can numpy.empty() create an empty array?

The answer is not, numpy.empty() function can not create an empty array.

Here is detail.

Understand numpy.empty(): It Cannot Create an Empty NumPy Array

## How to create an empty array?

To create an empty array is very easy in numpy. Here is an example:

import numpy as np

ex = np.array([], dtype = np.float32)
print(ex)
print(ex.shape)

The ex is:

[]
(0,)

## How to check a numpy array is empty or not?

We can use ndarray.size to check. Here is an tutorial.

Check a NumPy Array is Empty or not: A Beginner Tutorial

## Concatenate numpy empty array with other non-empty array

This is an very import tip for numpy programming. We can concatenate an empty array with other non-empty numpy array. Here is an example:

x2 = np.array([1, 2, 3, 4], dtype = np.float32)
x = np.concatenate((ex, x2), axis = 0)
print(x)

Here ex is an empty array, x2 is not empty. We can concatenate them. The result x is:

[1. 2. 3. 4.]

Similar to empty array, we also can create an empty matrix in numpy.

## How to create an empty matrix

We can create an empty numpy matrix as code below:

import numpy as np

em = np.mat([], dtype = np.float32)
print(em)
print(em.shape)

Here em is an empty numpy matrix. We also can use em.size to check a numpy matrix is empty or not.

em is:

[]
(1, 0)

Notice: you should notice the shape of empty array ex and empty matrix em is not.

 ex (0,) em (1,0)