Python NumPy Array Creation – Empty, Zeroes and Ones

In this tutorial, we will learn how to create an array in the Numpy Library.

In Numpy, a new ndarray object can be constructed by the following given array creation routines or using a low-level ndarray constructor.

  • numpy.empty
  • numpy.zeroes
  • numpy.ones

1. Empty Array – Using numpy.empty

This is used to create an uninitialized array of specified shape and dtype.

The syntax to use this constructor is as follows:

numpy.empty(shape, dtype, order)

Copy

Following is a description of parameters by this constructor:

  • shape: This parameter is used to indicate the desired shape of the specified array.
  • dtype: This parameter indicates the data type of the array items. The default value of this parameter is float.
  • order: The default order or value of this option is the c-style row-major order. This parameter can be set to F for FORTRAN-style (column-major order)

Using numpy.empty Basic Example:

The following code is used to create an empty array. Also, elements in an array will show random values because they are not initialized:

import numpy as np 

# an array with 4 rows and 3 columns
x = np.empty([4,3], dtype = int) 
print (x)

Output

[[206 0 0]

[ 0 0 0]

[ 0 0 0]

[ 0 0 0]]

2. Zero Value Array – Using numpy.zeroes

This is used to return a new array of the specified size and each array item will be initialized with 0.

The syntax to use this constructor is as follows:

numpy.zeros(shape, dtype, order)

Following is a description of parameters by this constructor:

  • shape: This parameter is used to indicate the desired shape of the specified array.
  • dtype: This parameter indicates the data type of the array items. The default value of this parameter is float.
  • order: The default order or value of this option is the c-style row-major order. This parameter can be set to F for FORTRAN-style (column-major order)

Using numpy.zeroes Basic Example:

The below code example will create an array of dimension 3×3 with all elements initialized as 0.

import numpy as np  

arr = np.zeros((3,3), dtype = int)  
print(arr)

Output:

[[0 0 0]

[0 0 0]

[0 0 0]]

3. One Value Array – Using numpy.ones

This is used to return a new array of the specified size and each array item will be initialized as 1.

The syntax to use this constructor is as follows:

numpy.ones(shape, dtype, order)

Following is a description of parameters by this constructor:

  • shape: This parameter is used to indicate the desired shape of the specified array.
  • dtype: This parameter indicates the data type of the array items. The default value of this parameter is float.
  • order: The default order or value of this option is the c-style row-major order. This parameter can be set to F for FORTRAN-style (column-major order)

Using numpy.ones Basic Example:

Here is a basic example:

import numpy as np  

arr = np.ones((3,3), dtype = int)  
print(arr)

Output:

[[1 1 1]

[1 1 1]

[1 1 1]]

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