The following syntax can be used to convert a Python list to a numpy array:
my_array = np.array(my_list)
In this guide, you’ll see how to convert:
- Python list to a numpy array
- List of lists (multi-dimensional list) to a numpy array
(1) Convert Python List to a NumPy Array
Let’s create a simple list with 6 elements:
my_list = [10,15,20,25,30,35] print(my_list) print(type(my_list))
This is how the list would look like:
[10, 15, 20, 25, 30, 35]
<class 'list'>
Notice that print(type(my_list)) was added at the bottom of the code in order to demonstrate that we created a list.
The goal is to convert that list to a numpy array.
To do so, you may use the template below:
my_array = np.array(my_list)
For our example, the complete code to convert the list to a numpy array is as follows:
import numpy as np my_list = [10,15,20,25,30,35] my_array = np.array(my_list) print(my_array) print(type(my_array))
As you can see, the list was converted to a numpy array:
[10 15 20 25 30 35]
<class 'numpy.ndarray'>
(2) Convert List of Lists to a NumPy Array
What if you have a list of lists (multi-dimensional list) and you’d like to convert it to a numpy array?
For example, let’s create the following list of lists:
my_list = [[10,15,20],[25,30,35]] print(my_list) print(type(my_list))
This is how the list of lists would look like:
[[10, 15, 20], [25, 30, 35]]
<class 'list'>
You can then apply the code below in order to convert the list of lists to a numpy array:
import numpy as np my_list = [[10,15,20],[25,30,35]] my_array = np.array(my_list) print(my_array) print(type(my_array)) print('Number of array dimensions: ' + str(my_array.ndim))
You’ll then get the following two-dimensional numpy array:
[[10 15 20]
[25 30 35]]
<class 'numpy.ndarray'>
Number of array dimensions: 2
Additional Sources
You may visit the NumPy Documentation to learn more about creating a numpy array.
For an opposite scenario, you may check the following guide that explains how to convert a numpy array to a list.