How can I reverse a list in python?

Question

How can i do this in python?

array=[0,10,20,40]
for (i = array.length() - 1 ;i >= 0; i--)

I need to have the elements of an array but from the end to the beginning.

Answer 1

You just need to think backwards.

for (i=array.length(); i>0; i--)

Answer 2

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

Extended slice syntax is explained well here: http://docs.python.org/release/2.3.5/whatsnew/section-slices.html

By special request in a comment this is the most current slice documentation.

Answer 3

for x in array[::-1]:
    do stuff

Answer 4

You can make use of the reversed function for this as:

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

Answer 5

>>> L = [0,10,20,40]
>>> L.reverse()
>>> L
[40, 20, 10, 0]

Or

>>> L[::-1]
[40, 20, 10, 0]

Answer 6

array=[0,10,20,40]
for e in reversed(array):
  print e

Answer 7

If you just use the array once (and can discard it), the most idiomatic solution is:

array = [0,10,20,40]
while array:
     item = array.pop()

Answer 8

The most direct translation of your requirement into Python is this for statement:

for i in xrange(len(array) - 1, -1, -1):
   print i, array[i]

This is rather cryptic but may be useful.