reverse python array - Brave Search

How do I reverse a list or loop over it backwards?

stackoverflow.com › questions › 3940128 › how-do-i-reverse-a-list-or-loop-over-it-backwards

To get a new reversed list, apply the reversed function and collect the items into a list:

>>> xs = [0, 10, 20, 40]
>>> list(reversed(xs))
[40, 20, 10, 0]

To iterate backwards through a list:

>>> xs = [0, 10, 20, 40]
>>> for x in reversed(xs):
...     print(x)
40
20
10
0

Answer from codaddict on Stack Overflow

geeksforgeeks.org › python › python-reversing-list

Reversing a List in Python - GeeksforGeeks

This method builds a reversed version of the list using slicing with a negative step. ... Python's built-in reversed() function is another way to reverse the list.

Published November 26, 2025

stackoverflow.com › questions › 3940128 › how-do-i-reverse-a-list-or-loop-over-it-backwards

python - How do I reverse a list or loop over it backwards? - Stack Overflow

To get a new reversed list, apply the reversed function and collect the items into a list:

>>> xs = [0, 10, 20, 40]
>>> list(reversed(xs))
[40, 20, 10, 0]

To iterate backwards through a list:

>>> xs = [0, 10, 20, 40]
>>> for x in reversed(xs):
...     print(x)
40
20
10
0

>>> xs = [0, 10, 20, 40]
>>> xs[::-1]
[40, 20, 10, 0]

Extended slice syntax is explained here. See also, documentation.

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Python documentation

docs.python.org › 3 › library › stdtypes.html

Built-in Types — Python 3.14.3 documentation

1 month ago - Forward and reversed iterators over mutable sequences access values using an index. That index will continue to march forward (or backward) even if the underlying sequence is mutated.

quora.com › How-do-I-reverse-an-array-in-Python

How to reverse an array in Python - Quora

Answer (1 of 3): Reverse an array in python Reverse an array in Python is simple. in python there is various method to reverse an array that is slicing method, using a reverse method, using the reversed method, etc. 1. Using Slicing method in python 3 : arr = [1,2,3,4,5,6,7,8,9,0] print(“the o...

askpython.com › home › reverse an array in python – 10 examples

Reverse an Array in Python - 10 Examples - AskPython

January 16, 2024 - In this tutorial, we'll go over the different methods to reverse an array in Python. The Python language does not come with array data structure support.

codecademy.com › article › how-to-reverse-a-list-in-python

How to Reverse a List in Python | Codecademy

Learn how to reverse a list in Python using `.reverse()`, `reversed()`, slicing, the two-pointer method, loops, and recursion with examples.

reddit.com › r/python › how to reverse a python list (3 methods)

r/Python on Reddit: How to reverse a Python list (3 methods)

February 19, 2022 -

There are three methods you can use to reverse a list:

An in-place reverse, using the built-in reverse method that every list has natively
Using list slicing with a negative step size, resulting in a new list
Create a reverse iterator, with the reversed() function

You can try this for yourself too. Click here to open a runnable/editable example.

Well don't forget about doing it by hand! print(list(lst[i] for i in range(-1, -len(lst)-1, -1)))

I know these Ways , is there any method more fast than them ?

Find elsewhere

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geeksforgeeks.org › python › python-reverse-a-numpy-array

Reverse a Numpy Array - Python - GeeksforGeeks

September 20, 2025 - The numpy.flip() function reverses the order of array elements along the specified axis.

geeksforgeeks.org › python › reverse-a-list-in-python-without-using-reverse-function

Reverse a List in Python Without Using reverse() Function - GeeksforGeeks

July 23, 2025 - List comprehension is a more compact way to reverse a list by iterating over the original list in reverse order and constructing a new list.

w3schools.com › python › ref_list_reverse.asp

Python List reverse() Method

Python Examples Python Compiler ... Q&A Python Bootcamp Python Certificate Python Training ... The reverse() method reverses the sorting order of the elements....

note.nkmk.me › home › python

Reverse a List, String, Tuple in Python: reverse, reversed | note.nkmk.me

August 16, 2023 - In Python, you can reverse a list using the reverse() method, the built-in reversed() function, or slicing. To reverse a string (str) and a tuple, use reversed() or slicing. Reverse a list using the r ...

tutorialspoint.com › python › python_reverse_arrays.htm

Python - Reverse Arrays

Reversing an array is the operation of rearranging the array elements in the opposite order. There are various methods and approaches to reverse an array in Python including reverse() and reversed() methods.

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › Array › reverse

Array.prototype.reverse() - JavaScript | MDN

The reverse() method of Array instances reverses an array in place and returns the reference to the same array, the first array element now becoming the last, and the last array element becoming the first. In other words, elements order in the array will be turned towards the direction opposite ...

ioflood.com › blog › python-reverse-list

Python Reverse List: Complete Guide (With Examples)

June 17, 2024 - In this example, we import the NumPy library and use its flip() function to reverse my_list. The tolist() function then converts the NumPy array back to a Python list.

stackoverflow.com › questions › 6771428 › most-efficient-way-to-reverse-a-numpy-array

python - Most efficient way to reverse a numpy array - Stack Overflow

reversed_arr = arr[::-1]

gives a reversed view into the original array arr. Any changes made to the original array arr will also be immediately visible in reversed_arr. The underlying data buffers for arr and reversed_arr are shared, so creating this view is always instantaneous, and does not require any additional memory allocation or copying for the array contents.

See also, this discussion on NumPy views: How do I create a view onto a NumPy array?

Possible solutions to performance problems regarding views

Are you re-creating the view more often than you need to? You should be able to do something like this:

arr = np.array(some_sequence)
reversed_arr = arr[::-1]

do_something(arr)
look_at(reversed_arr)
do_something_else(arr)
look_at(reversed_arr)

I'm not a numpy expert, but this seems like it would be the fastest way to do things in numpy. If this is what you are already doing, I don't think you can improve on it.

a[::-1]

only creates a view, so it's a constant-time operation (and as such doesn't take longer as the array grows). If you need the array to be contiguous (for example because you're performing many vector operations with it), ascontiguousarray is about as fast as flipud/fliplr:

Code to generate the plot:

import numpy
import perfplot


perfplot.show(
    setup=lambda n: numpy.random.randint(0, 1000, n),
    kernels=[
        lambda a: a[::-1],
        lambda a: numpy.ascontiguousarray(a[::-1]),
        lambda a: numpy.fliplr([a])[0],
    ],
    labels=["a[::-1]", "ascontiguousarray(a[::-1])", "fliplr"],
    n_range=[2 ** k for k in range(25)],
    xlabel="len(a)",
)

medium.com › @ryan_forrester_ › python-array-reverse-complete-guide-37f508724621

Python Array Reverse: Complete Guide | by ryan | Medium

October 28, 2024 - Let’s explore the different ways to reverse lists in Python, with practical examples you can use in your own code. The `reverse()` method is Python’s built-in solution for flipping lists.

freecodecamp.org › news › python-sort-lists-and-reverse-arrays

Python Sorted List – And How to Sort or Reverse an Array in Python

February 24, 2023 - How to sort a list in Python. Using the sort() method. Using the sorted() function. Using the heapq module. Reversing an array is often a more effective brute-force approach for a variety of issues.

programiz.com › python-programming › methods › list › reverse

Python List reverse()

# List Reverse systems.reverse() # updated list print('Updated List:', systems)

Data Science Dojo

discuss.datasciencedojo.com › python

How to reverse an array? - Python - Data Science Dojo Discussions

February 14, 2023 - Hey everyone. I need your help. This is my vector [1,2,3,4,5] . I want to invert in a way that the last value comes first and so on. I used the list function but that is on applicable to Python’s built-in List and not w…

visualgo.net › en › array

Array - VisuAlgo

Visualization of one of the simplest data structure in Computer Science: Array (and its sorted form) surprisingly has not been done in VisuAlgo since its inception 2011-January 2024...Stay tuned while we improve this page and its features.