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You can use one of the following methods to add a column to a NumPy array:

**Method 1: Append Column to End of Array**

np.append(my_array, [[value1], [value2], [value3], ...], axis=1)

**Method 2: Insert Column in Specific Position of Array**

np.insert(my_array, 3, [value1, value2, value3, ...], axis=1)

The following examples show how to use each method in practice.

**Example 1: Append Column to End of NumPy Array**

Suppose we have the following NumPy array:

import numpy as np #create NumPy array my_array = np.array([[1, 2, 3, 4], [5, 6, 7, 8]]) #view NumPy array my_array array([[1, 2, 3, 4], [5, 6, 7, 8]])

We can use the following syntax to add a column to the end of the NumPy array:

#append column to end of NumPy array new_array = np.append(my_array, [[10], [13]], axis=1) #view updated array new_array array([[ 1, 2, 3, 4, 10], [ 5, 6, 7, 8, 13]])

**Example 2: Insert Column in Specific Position of NumPy Array**

Suppose we have the following NumPy array:

import numpy as np #create NumPy array my_array = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) #view NumPy array my_array array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])

We can use the following syntax to insert a new column before the column in index position 2 of the NumPy array:

#insert new column before column in index position 2 new_array = np.insert(my_array, 2, [10, 13, 19], axis=1) #view updated array new_array array([[ 1, 2, 10, 3], [ 4, 5, 13, 6], [ 7, 8, 19, 9]])

Notice that the new column of values has been inserted before the column in index position 2.

**Additional Resources**

The following tutorials explain how to perform other common operations in NumPy:

How to Add a Numpy Array to a Pandas DataFrame

How to Convert Pandas DataFrame to NumPy Array