Python NumPy empty array with examples

In this Python tutorial, we will discuss Python NumPy empty array with a few examples like below:

  • Python numpy empty array append
  • Python numpy array empty check
  • Python empty numpy array without shape
  • Python numpy empty 2d array
  • Python numpy concatenate empty array
  • Python numpy declare empty array
  • Python numpy empty string array
  • Python numpy empty 3d array
  • Python fill empty numpy array
  • Python Create Empty Numpy array and append rows
  • Python Create Empty Numpy array and append Columns

Python numpy empty array

  • In this section, we will discuss Python numpy empty array, specially how to create an empty array using Python NumPy.
  • In this method we can easily use the function np.empty().
  • The NumPy empty() function is used to create an array of given shapes and types, without initializing values.
  • To work with arrays, python provides a numpy empty array function. It is used to create an empty array as per user condition means given data type and shape of the array without initializing values.
  • It allows only shape and data type as arguments. If the datatype parameter is not provided then the default data type of all Values in the returned array will be float.

Syntax:

Here is the Syntax of numpy.empty()

numpy.empty
           (
            shape,
            dtype=float,
            order='C'
           )
  • It Consists of few parameters.
    • Shape: Shape of the empty array, e.g:(4,3)
    • dtype: its an optional parameter by default value is float.
    • order: Whether to store multi-dimensional numpy array data in row and column-wise.

Example:

  • Let’s take an example to check how to implement a numpy empty array
  • Basically there are two ways to check numpy empty array.
    • Using numpy empty array function.
    • Using numpy zero’s array function

Using numpy empty array function

In this example, we implement an array empty function. But empty function does not mean that the array values will be zeros.

import numpy as np

arr = np.empty(5)
print(arr)

In the above code, we implement a simple NumPy empty array and it always returns uninitialized values with shape and data type.

Here is the Screenshot of the following given code

Python numpy empty array
Python numpy empty array

To create an empty array, we can easily pass the empty list to the numpy. array() method and it will make the empty array.

Example:

import numpy as np

list = []
arr = np.array(list)
print(arr)

Here is the Screenshot of the following given code

Python NumPy empty array
Create numpy empty array

This is how to create an empty array using Python NumPy.

Using numpy zero’s array function

  • In this method, we implement a numpy zero’s array function.
  • This method returns a new array of given shapes and datatypes, with zeros.

Syntax:

Here is the Syntax of numpy zeros() function

numpy.zeros
           (
            shape,
            dtype = None, 
            order = 'C' 
           )

Example:

import numpy as np

arr = np.zeros([2,2],dtype='int')
print(arr)

Here is the Screenshot of the following given code

Python numpy empty array by using zeros
Python numpy empty array by using zeros

This is how to create a NumPy array by using zeros.

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Python numpy empty array append

  • In this section, we will discuss Python numpy empty array append.
  • In this method we can easily use the function numpy.append().
  • The np. append() function allows us to contain new values to the end of an existing NumPy array.
  • This method returns a copy of the present array with the values concatenates to the specified axis.
  • If we have an array and want to append rows to it inside a loop, we can easily use the np. empty() function.
  • Now, we can then append new rows to the empty array with numpy.append() function.

Example:

Let’s take an example to check how to implement a numpy empty array with append.

import numpy as np

arr = np.empty((0,3), int)

arr2 = np.append(arr, np.array([[2,4,5]]), axis=0)
array = np.append(arr2, np.array([[7,8,9]]), axis=0)

print(array)

In the above code, we will create an empty numpy array by using the function numpy. empty() and define its datatype.Now we can easily append two rows along the 0 axis by using the function np.append()

Here is the Screenshot of the following given code

Python numpy empty array append
Python numpy empty array append

Read Python NumPy zeros

Python numpy empty array append example

  • In this section, we will discuss the numpy empty array append.
  • In this example, we can easily use the function numpy. append().
  • The list. append() method concatenates an element to the last of the list.
  • We can then convert this list to a numpy array by using np. array() function.

Example:

import numpy as np

list = []
list.append([2,4,6])
list.append([9,5,7])
arr2 = np.array(list)
print(arr2)

Here is the Screenshot of the following given code

Python numpy empty array append list method
Python numpy empty array append list method

Python numpy array empty check

If you want to check if a NumPy array is empty or not, follow an article on Check if NumPy Array is Empty in Python.

Python empty numpy array without shape

  • In this section, we will discuss Python empty numpy array without shape.
  • In this example, we can easily use the function np. append() to get the empty numpy array without shape.
  • First, we will create a list and convert that to an array and take a variable y which is iterable.
  • It doesn’t accept shape and datatype as a parameter.

Example:

import numpy as np
y=[]
a = np.array([2,3,4,5])
for x in y:
    a = np.append(a, x)
print(y)

Here is the Screenshot of the following given code

Python empty numpy array without shape
Python empty numpy array without shape

The above code we can use to create empty NumPy array without shape in Python.

Read Python NumPy nan

Python numpy empty 2d array

  • In this section, we will discuss Python numpy empty 2d array.
  • To create an empty 2Dimensional array we can pass the shape of the 2D array ( i.e is row and column) as a tuple to the empty() function.
  • In this example, we can easily use the function np. empty().
  • It takes only shape and data type as arguments.
  • It returns an empty 2dimesion array of rows and columns but all elements in this 2d array were not initialized.
  • In this example, we did not provide data type as an argument by default it takes the value as afloat.

Syntax:

numpy.empty
           (
            shape,
            dtype=float,
            order='C'
           )

Example:

import numpy as np
arr = np.empty((4, 3), int)
print('Empty 2D Numpy array:')
print(arr)

In the above code, we will import the numpy library and create an empty 2dimension numpy array with 4 rows and 3 columns and print the result.

Here is the Screenshot of the following given code

Python numpy empty 2d array method
Python numpy empty 2d array method

This is how to create an empty 2D Numpy array in Python.

Read Valueerror: Setting an array element with a sequence

Python numpy concatenate empty array

  • In this section, we will discuss Python numpy concatenate empty array.
  • We need to create an array of a specified size m*n where m is the number of rows and n is a number of columns filled with empty values so that when we append to that array the initial values exist.
  • In this method we can easily use the function numpy.concatenate().
  • This method is used to join two or more given arrays along the axis.
  • The numpy. concatenate() function concatenate an element to the last of the list.
  • In this method, we can easily use both functions np. concatenate and np. empty() to get the empty array.

Example:

import numpy as np
a = np.empty([2,2])  
b = np.array([[4,5],[6,7]])    
arr = np.concatenate((a,b)) 
print(arr)  

Here is the Screenshot of the following given code

Python numpy concatenate empty array
Python numpy concatenate empty array

The above code we can use to concatenate empty array in Python NumPy.

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Python numpy declare empty array

  • In this section, we will discuss Python numpy declare empty array.
  • In this method we can easily use the function numpy.empty().
  • The np.empty() function is used to create a new array of given shapes and types, without initializing entries.

Syntax:

Here is the Syntax of numpy.empty()

numpy.empty
           (
            shape,
            dtype=float,
            order='C'
           )

Example:

To create an empty NumPy array of some specified data type, we can pass that data type as a dtype parameter in the empty() function.

import numpy as np
a = np.empty([2,2], dtype= complex) 
print(a) 

In the above code, we will create an empty numpy array of complex numbers, we need to pass the complex value as a dtype argument in the numpy.empty() function.

Here is the Screenshot of the following given code

Python numpy declare empty array
Python numpy declare empty array

This is how to declare empty array using Python NumPy.

Declare numpy empty array in Python

To create an empty array of integers, we need to pass an integer as a dtype argument in the np. empty() function.

Example:

import numpy as np
a = np.empty([3,3], dtype= 'int') 
print(a) 

In the above code, we will create an empty array of integers numbers, we need to pass int as dtype parameter in the NumPy.empty() function.

Here is the Screenshot of the following given code

Python numpy declare empty array integer method
Python numpy declare empty array integer method

This is how to create an empty NumPy array of integers.

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Python numpy empty string array

  • In this section, we will discuss Python numpy empty string array.
  • To create an empty array of strings we can easily use the function np. empty().
  • To create an empty array of 4 strings (with size 3), we need to pass ‘S3’ as a dtype argument in the np. empty() function.
  • It takes only shape and data type as arguments.

Example:

Let’s take an example to check how to create a numpy empty string array

import numpy as np

array = np.empty(4, dtype='S3')
print(array)

Here ‘S3’ represents to “Unicode string of length 3

Here is the Screenshot of the following given code

Python numpy empty string array
Python numpy empty string array

The above code we can use to create an empty string array in Python using NumPy.

Python numpy empty 3d array

  • In this section, we will discuss Python numpy empty 3d array.
  • To create an empty 3Dimension array we can pass the shape of the 3Dimension array as an open bracket to the empty() function.
  • In this example, we can easily use the function np.empty() to get the empty 3dimension array.
  • Let’s create an empty 3Dimension array with a matrix of 3 rows and 3 columns.
  • In this function, we didn’t provide any data type as an argument. But all the values in the 3Dimension array were not initialized.

Example:

import numpy as np

array = np.empty((1, 3, 3)) # where 1 is the length of matrix
print(array)

In the above example code, we will import a library and create an empty numpy array in which we assign a parameter as the length of the matrix which is 1, and a number of rows and columns.

Here is the Screenshot of the following given code

Python numpy empty 3d array
Python numpy empty 3d array

This is an example of a Python NumPy empty 3d array.

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Python fill empty numpy array

  • In this section, we will discuss Python fill empty numpy array.
  • In this method we can easily use the function numpy.empty().
  • When you create an array with numpy. empty, You need to specify the same shape argument in the output by using the shape parameter.
  • Let’s create an empty array and use the method a.fill().
  • fill() method is used to fill the array with a scalar and vector value.
  • In this method, we didn’t need to use loops to initialize a numpy array if we are using this fill() function.

Example:

import numpy as np

a = np.empty(4)
a.fill(3)
print(a)

Here is the Screenshot of the following given code

Python fill empty numpy array
Python fill empty numpy array

The above code we can use to fill empty NumPy array in Python.

Python Create an Empty Numpy array and append rows

  • In this section, we will discuss Empty Numpy array and append rows.
  • In this method, first, we will create an empty numpy array with 4 columns and 0 rows.
  • Now to concatenate a new row to this empty 2dimension array, we can use the numpy. append().
  • But we need to pass the row as an array of the same shape only and pass axis=0 so that it can be concatenated along the column.

Example:

import numpy as np

arr = np.empty((0, 4), int)
print('Empty 2D Numpy array:')
print(arr)
# Append a row to the 2D numpy array
emp_arr = np.append(arr, np.array([[4, 3, 6, 7]]), axis=0)
# Append 2nd rows to the 2D Numpy array
emp_arr = np.append(emp_arr, np.array([[2, 6, 9, 10]]), axis=0)
print('2D Numpy array:')
print(emp_arr)

In the above code, our 2Dimension array had 4 columns, therefore to insert a new row we need to pass this row as a separate 2Dimension array with dimension (2,4).

Here is the Screenshot of the following given code

Python Create an Empty Numpy array and append rows
Python Create an Empty Numpy array and append rows

The above code we can use to Create an Empty Numpy array and append rows in Python.

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Python Create Empty Numpy array and append Columns

  • In this section, we will discuss the Empty Numpy array and append columns.
  • In this method, first, we will create an empty numpy array with 0 columns and 4 rows.
  • Now to concatenate a new column to this empty 2Dimension array, we can easily use the np. append().
  • But we need to pass the column as a numpy array of the same shape only an argument axis=1 so that it can be appended along the column.

Example:

import numpy as np

arr = np.empty((4, 0), int)
print('Empty 2D Numpy array:')
print(arr)
# Column list1
emp_arr = np.append(arr, np.array([[4, 3, 6, 7]]).transpose(), axis=1)

print('2D Numpy array:')
print(emp_arr)

In the above code, our empty numpy array has 4 rows & 0 columns, so to insert a new column we need to pass this column as a separate 2Dimension array with dimension (4,1).

Here is the Screenshot of the following given code

Python Create Empty Numpy array and append Columns
Python Create Empty Numpy array and append Columns

The above code we can use to create an empty Numpy array and append Columns in Python.

You may like the following Python tutorials:

In this Python tutorial, we will discuss Python NumPy empty array with a few examples like below:

  • Python numpy empty array append
  • Python numpy array empty check
  • Python empty numpy array without shape
  • Python numpy empty 2d array
  • Python numpy concatenate empty array
  • Python numpy declare empty array
  • Python numpy empty string array
  • Python numpy empty 3d array
  • Python fill empty numpy array
  • Python Create Empty Numpy array and append rows
  • Python Create Empty Numpy array and append Columns