How to append a NumPy array to an empty array in Python Last Updated : 30 Dec, 2022 Summarize Comments Improve Suggest changes Share Like Article Like Report In this article, we will cover how to append a NumPy array to an empty array in Python. Here, we will discuss 2 different methods to append into an empty NumPy array. Both of these methods differ slightly, as shown below: Append a NumPy array to an empty array using the appendExample 1 Here we are creating an empty array and then appending it to the array. Python3 import numpy as np l = np.array([]) l = np.append(l, np.array(['G', 'F', 'G'])) l = np.append(l, np.array(['G', 'F', 'G'])) print(l) Output: ['G' 'F' 'G' 'G' 'F' 'G']Example 2 Here we are creating an empty array and then appending an empty row in it to see if there is any difference. Python3 import numpy as np l = np.array([]) l = np.append(l, np.array([])) l = np.append(l, np.array(['G', 'F', 'G'])) l = np.append(l, np.array(['G', 'F', 'G'])) print(l) Output: We can see that there is no difference in output. ['G' 'F' 'G' 'G' 'F' 'G']Append a NumPy array to an empty array using hstack and vstack Here we are using the built-in functions of the NumPy library np.hstack and np.vstack. Both are very much similar to each other as they combine NumPy arrays together. The major difference is that np.hstack combines NumPy arrays horizontally and np. vstack combines arrays vertically. Python3 import numpy as np arr = np.array([]) arr = np.hstack((arr, np.array(['G', 'F', 'G']))) print(arr) arr = np.vstack((arr, np.array(['G', 'F', 'G']))) print(arr) Output: ['G' 'F' 'G'] [['G' 'F' 'G'] ['G' 'F' 'G']] Comment More infoAdvertise with us Next Article How to append a NumPy array to an empty array in Python S shlokdi35dq Follow Improve Article Tags : Python Numpy Practice Tags : python Similar Reads How to create an empty and a full NumPy array? Creating arrays is a basic operation in NumPy. Empty array: This array isnât initialized with any specific values. Itâs like a blank page, ready to be filled with data later. However, it will contain random leftover values in memory until you update it.Full array: This is an array where all the elem 2 min read How to Copy NumPy array into another array? Many times there is a need to copy one array to another. Numpy provides the facility to copy array using different methods. In this Copy NumPy Array into Another ArrayThere are various ways to copies created in NumPy arrays in Python, here we are discussing some generally used methods for copies cre 2 min read How to create an empty matrix with NumPy in Python? In Python, an empty matrix is a matrix that has no rows and no columns. NumPy, a powerful library for numerical computing, provides various methods to create matrices with specific properties, such as uninitialized values, zeros, NaNs, or ones. Below are different ways to create an empty or predefin 3 min read How to Add a New Value to a NumPy Array Let's learn how to add a new value to a Numpy array. Adding elements in a NumPy array is not straightforward compared to adding them to standard Python lists. Adding Values to NumPy Array using np.append()The np.append() function is used to add new values at the end of an existing NumPy array. This 2 min read How to append two NumPy Arrays? Prerequisites: Numpy Two arrays in python can be appended in multiple ways and all possible ones are discussed below. Method 1: Using append() method This method is used to Append values to the end of an array. Syntax : numpy.append(array, values, axis = None) Parameters : array: [array_like]Input a 4 min read Like