Introduction:

NumPy is a powerful library in Python for numerical computations, offering support for large, multi-dimensional arrays and matrices. However, there are times when you may need to work with standard Python lists instead of NumPy arrays. Converting between the two data structures is a common task in data manipulation and analysis workflows. In this blog, we will explore various methods to convert NumPy arrays to lists in Python.

Method 1: Using the tolist() method

To convert a NumPy array to a list is by using the tolist() method provided by NumPy arrays. This method converts the array into a Python list, preserving the array's shape and elements.

import numpy as np

# Create a NumPy array
numpy_array = np.array([1, 2, 3, 4, 5])

# Convert the NumPy array to a list
list_from_array = numpy_array.tolist()

# Output the converted list
print("Converted List:", list_from_array)

Output:

Converted List: [1, 2, 3, 4, 5]

• In this method, we first create a NumPy array using the np.array() function.
• Then, we call the tolist() method on the NumPy array to convert it into a Python list.
• Finally, we print the converted list to verify the conversion.

Method 2: Using the numpy.ndarray.tolist() function

Another way to convert a NumPy array to a list is by directly using the numpy.ndarray.tolist() function. This function behaves similarly to the tolist() method but can be called directly on the NumPy array object.

import numpy as np

# Create a NumPy array
numpy_array = np.array([6, 7, 8, 9, 10])

# Convert the NumPy array to a list using ndarray.tolist()
list_from_array = np.ndarray.tolist(numpy_array)

# Output the converted list
print("Converted List:", list_from_array)

Output:

Converted List: [6, 7, 8, 9, 10]

• Here, we create a NumPy array using np.array().
• We then use np.ndarray.tolist() function, passing the NumPy array as an argument, to directly convert it into a Python list.
• Finally, we print the converted list to confirm the conversion.

Method 3: Using list comprehension

List comprehension offers a concise and efficient way to convert each element of a NumPy array into a list. By iterating over the array's elements, we can construct a new list containing the same elements.

import numpy as np

# Create a NumPy array
numpy_array = np.array([11, 12, 13, 14, 15])

# Convert the NumPy array to a list using list comprehension
list_from_array = [element for element in numpy_array]

# Output the converted list
print("Converted List:", list_from_array)

Output:

Converted List: [11, 12, 13, 14, 15]

• In this method, we utilize list comprehension to iterate over each element in the NumPy array.
• For each element, we add it to the new list.
• Finally, we print the converted list to verify the conversion.

Conclusion:

In this blog, we explored multiple methods to convert NumPy arrays to lists in Python. Whether you prefer using built-in methods like tolist() or numpy.ndarray.tolist(), or opt for list comprehension for more flexibility, Python offers various approaches to suit your needs.