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Lists and arrays are the two most basic and commonly used collection objects in Python.

They are both mutable and are used to store a collection of elements under a common name and each element has a specific location that can be used to access it.

However, there are some significant differences. Lists are already built-in in Python, whereas for arrays, we need to import the arraysor NumPymodule and declare the arrays before using them. Arrays also store data in memory more efficiently and are widely used for mathematical operations.

In this tutorial, we will convert a numpy array to a list.

tolist()To convert a NumPy array to a list, use

The NumPy array tolist()method can convert a NumPy array to a list.

For example,

import numpy as np

oned = np.array([[1, 2, 3]])
twod = np.array([[1, 2, 3], [4, 5, 6]])

print(oned.tolist())
print(twod.tolist())

Output:

[[1, 2, 3]]
[[1, 2, 3], [4, 5, 6]]

Note that this method treats the entire array as one element. That's why when we use it with a two-dimensional array, it returns a list of lists.

To avoid this, we can use tolist()with flatten()or ravel()methods, which can convert an ND array into a linear 1D array. Both methods perform the same function. The difference is that ravel()the method returns a reference view of the array and affects the original array, while flatten()the method works on a copy of the array. Therefore, ravel()the function is considered faster and occupies less memory.

The following code shows the usage of these functions.

import numpy as np

oned = np.array([1, 2, 3])
twod = np.array([[1, 2, 3], [4, 5, 6]])

print(oned.flatten().tolist())
print(twod.flatten().tolist())


print(oned.ravel().tolist())
print(twod.ravel().tolist())

Output:

[1, 2, 3]
[1, 2, 3, 4, 5, 6]
[1, 2, 3]
[1, 2, 3, 4, 5, 6]

forConvert NumPy array to list in Python using loop

This is just a basic approach for those who are new to programming or want to customize the final list. We iterate over an array and append each element individually to an empty list. The following code achieves this.

import numpy as np

arr = np.array([1, 2, 3])
lst = []

for x in arr:
    lst.append(x)

print(lst)

Output:

[1, 2, 3]