How to create empty array python

How to Create an Empty Array in Python: A Guide to Using Lists and Numpy

Learn how to initialize an empty array in Python using lists and the numpy module. Explore examples and best practices for working with arrays in Python. Get started now!

Python is a powerful programming language that is widely used in different fields, including data science, machine learning, and web development. One of the most useful data structures in Python is an array, which is essentially a collection of elements of the same data type. However, Python does not have built-in support for arrays. Instead, lists can be used as arrays, while the numpy module provides powerful tools for working with arrays. In this article, we will explore how to initialize an empty array in Python, with a focus on using lists and the numpy module.

Using Lists as Arrays

In Python, a list can be used as an array. To create an empty list, simply declare an empty list using square brackets:

To create an empty list of a specific size, one can create a list with the desired number of elements (such as [None]*length ). For example, the following code creates an empty list of size 5:

Lists can be accessed using indexing, with the first element having an index of 0. Lists can also be sliced, with the syntax list[start:end:step] .

Using numpy.empty()

Numpy is a powerful numerical computing library for Python. Numpy provides a numpy.empty() function that creates a new array without initializing entries. The function takes shape and data type as arguments. For example, the following code creates an empty numpy array of size 5:

import numpy as npmy_array = np.empty(5, dtype=int) 

The size of a numpy array can be obtained using the size attribute, while the shape attribute returns the shape of a numpy array (i.e., its dimensions). For example, the following code gets the shape and size of a numpy array:

shape = my_array.shape size = my_array.size 

Using numpy.empty_like()

Numpy provides the numpy.empty_like() function, which creates an empty array with the same shape and data type as an existing array. For example, the following code creates an empty numpy array with the same shape and data type as an existing array:

new_array = np.empty_like(old_array) 

Checking if an Array is Empty

The len() method returns the length of a list. To check if a list is empty, one can use the len() method. For example, the following code checks if a list is empty:

To check if a numpy array is empty, one can use the size attribute. For example, the following code checks if a numpy array is empty:

Additional Helpful Points

Here are some additional helpful points to keep in mind when working with arrays in Python:

• Cheatsheets for Numpy and Python can be useful references for working with arrays.
• When working with large datasets, using numpy arrays instead of lists can result in faster computation times.
• It is generally better to initialize a numpy array with zeros or ones instead of empty values.
• To add elements to an existing array, one can use functions like numpy.append() or numpy.concatenate() .
• To remove elements from an existing array, one can use functions like numpy.delete() or numpy.trim_zeros() .
• When working with multidimensional arrays, one can use functions like numpy.reshape() or numpy.transpose() to manipulate their shape or dimensions.
• Using descriptive variable names can make it easier to understand and maintain code that involves arrays.

Other simple code examples for empty arrays in Python

In Python , in particular, how to create a fixed size empty array in python

In Python , in particular, python declare array of size n code sample

>>> n = 5 #length of list >>> list = [None] * n #populate list, length n with n entries "None" >>> print(list) [None, None, None, None, None]>>> list.append(1) #append 1 to right side of list >>> list = list[-n:] #redefine list as the last n elements of list >>> print(list) [None, None, None, None, 1]>>> list.append(1) #append 1 to right side of list >>> list = list[-n:] #redefine list as the last n elements of list >>> print(list) [None, None, None, 1, 1]>>> list.append(1) #append 1 to right side of list >>> list = list[-n:] #redefine list as the last n elements of list >>> print(list) [None, None, 1, 1, 1] 

In Python , in particular, empty array python

import numpy my_array = numpy.zeros(shape=(row,column))

In Python as proof, length of an empty array in python code example

>>> arrray = [] >> print(len(array)) 0

Conclusion

In conclusion, there are several ways to initialize an empty array in Python. Lists can be used as arrays, and numpy provides functions for creating arrays with specific shapes and data types. Checking if an array is empty can be done using the len() method for lists and the size attribute for numpy arrays. When working with arrays, it is important to use descriptive variable names and to be mindful of the size and shape of the array. By following these guidelines, you can create efficient and effective Python code that makes use of arrays.

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Initialize an empty array in Python

In this Python tutorial, We will discuss how built-in support works for the array in Python.

There are multiple ways to create an empty array in Python, which are shown below:

• Using the square brackets
• Using the array module
• Using the NumPy module
• Using the collections module
• Using the empty method
• Using the zeros method
• Using the full method
• Using the arange() method

Create empty array Python

Here we will see how to create an empty array in Python using a variety of different methods. Let us start with the first one.

Method-1: Create empty array Python using the square brackets

The simplest way to create an empty array in Python is to define an empty list using square brackets.

The above code creates an empty list object called empty_array. This list can be used to store elements and perform operations on them.

Method-2: Create empty array Python using the array module

The array module provides a way to create arrays with a specific data type. To create an empty array with the array module, you can call the array function and pass an empty list as the data argument.

# Importing the array module import array # Creating an empty array with data type 'i' (signed integer) empty_array = array.array('i') 

The above code imports the array module and creates an empty integer array, named empty_array, using the array constructor. The ‘i’ argument specifies that the elements of the array should be integers.

Method-3: Create empty array Python using the NumPy module

The numpy module is a powerful library for working with arrays in Python. To create an empty array with the numpy module, you can call various methods, such as empty, zeros, or ones, and pass a shape argument that specifies the dimensions of the array.

# Import numpy library import numpy as np # Creating an empty numpy array empty_array = np.array([]) 

The above code imports the numpy library as np and creates an empty numpy array with the np.array function and an empty list as an argument. The empty numpy array is stored in the empty_array variable.

Method-4: Create empty array Python using the collections module

The collections module provides a way to create arrays with a specific data type, similar to the array module. To create an empty array with the collections module, you can call the array function and pass an empty list as the data argument.

# Importing the 'array' module from the 'collections' library from collections import array # Creating an empty array with type code 'i' for signed integers empty_array = array('i') 

The above code is written in Python and it creates an empty array using the array module from collections. The array is created as an array of signed integers (‘i’) using the array constructor. The variable empty_array will store the reference to the newly created array.

Method-5: Create empty array Python using the empty method

The empty method from the numpy module creates an array with uninitialized data. To create an empty array with this method, you can call the empty method and pass a shape argument that specifies the dimensions of the array.

# Import numpy module import numpy as np # Create an empty numpy array with size 0 empty_array = np.empty(0) 

The above code imports the NumPy library as np and creates an empty array using the empty method from the numpy library.

The method takes in a single argument 0 which is the shape of the array. The empty array created will have a shape of (0,), meaning it has 0 rows and 1 column.

Method-6: Create empty array Python using the zeros method

The zeros method from the numpy module creates an array filled with zeros. To create an empty array with this method, you can call the zeros method and pass a shape argument that specifies the dimensions of the array.

# Importing the numpy module import numpy as np # Creating an empty array using np.zeros empty_array = np.zeros(0) 

The above code creates an empty numpy array with data type float (default data type in numpy) using the np. zeros function from the numpy library.

• The np.zeros function creates a new array of given shape and type, filled with zeros. In this case, the shape of the array is 0 which means an empty array.

Method-7: Create empty array Python using the full method

The full method from the numpy module creates an array filled with a specified value. To create an empty array with this method, you can call the full method and pass a shape argument that specifies the dimensions of the array, as well as the value to fill the array with.

import numpy as np # Import the numpy library # Create an empty numpy array with zero elements, initialized to None empty_array = np.full(0, None) 

In the above code, the numpy library is being imported and an empty numpy array is being created with zero elements, all initialized to None.

Method-8: Create empty array Python using the arange() method

To create an empty NumPy array using the arange() method, you can set the start and end values to the same value.

import numpy as np # Define the size of the array n = 10 # Define the starting and ending points of the array start = end = 0 # Create an array of integers of length `n` with values ranging from `start` to `end` my_array = np.arange(start, end, dtype=np.int32) 

The code above uses the NumPy library to create an array of integers. The n variable determines the size of the array, while the start and end variables determine the range of values that will be included in the array.

You may also like to read the following Python tutorials.

In this tutorial, we learned how to create an empty array in python by using the following methods:

• Using the square brackets
• Using the array module
• Using the NumPy module
• Using the collections module
• Using the empty method
• Using the zeros method
• Using the full method
• Using the arange() method

I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.

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