Hướng dẫn array of lists python

In this post, you will learn how to convert an array to a list using Python.

Nội dung chính

• Converting array to list using numpy tolist() method
• Converting multi-dimensional array to list
• Converting array to list using array class
• Related Articles

Nội dung chính

• Converting array to list using numpy tolist() method
• Converting multi-dimensional array to list
• Converting array to list using array class
• Related Articles

In Python, array and list are mostly used data structure. An array is a container which can hold a fixed number of items, and these items should be of the same type. A list is a sequence of indexed and ordered values. It contains a list of any type of data objects with a comma separated and enclosed within a square bracket. In the development process, we may come to the situation where we need to convert an array to a list. Python provides in-build method tolist() to convert an array to a list.

If the array is one-dimensional, a list with the array elements is returned, and if the array is multi-dimensional, a nested list is returned.

Converting array to list using numpy tolist() method

We can convert an array to the list of data elements with the help of ndarray.tolist() method. The numpy ndarray object has a handy tolist() method that can be used to convert the respect numpy array to a list. This method doesn't accept any argument and returns a copy of the array data as a Python list.

In the given example, we have converted the one-dimensional numpy array to a list.

Converting multi-dimensional array to list

In the given example, we have converted a multidimensional array to the list of data elements with the help of tolist() method.

Converting array to list using array class

Here, first we are importing an array class to use an array. Then, we convert an array to the list of data elements with the help of tolist() method.

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During programming, there will be instances when you will need to convert existing lists to arrays in order to perform certain operations on them (arrays enable mathematical operations to be performed on them in ways that lists do not).

Lists can be converted to arrays using the built-in functions in the Python numpy library.

numpy provides us with two functions to use when converting a list into an array:

• numpy.array()

• numpy.asarray()

This function of the numpy library takes a list as an argument and returns an array that contains all the elements of the list. See the example below:

import numpy as np my_list = [2,4,6,8,10] my_array = np.array(my_list) # printing my_array print my_array # printing the type of my_array print type(my_array)

This function calls the numpy.array() function inside itself. See the definition below:

The main difference between np.array() and np.asarray() is that the copy flag is false in the case of np.asarray(), and true (by default) in the case of np.array().

This means that np.array() will make a copy of the object (by default) and convert that to an array, while np.asarray() will not.

The code below ​illustrates the usage of np.asarray():

import numpy as np my_list = [2,4,6,8,10] my_array = np.asarray(my_list) # printing my_array print my_array # printing the type of my_array print type(my_array)