how to reverse a list and store in another list in python

[SuperNinja3I3]

I want to reverse a list but want to store it in another list...

reverse the elements of the ‘myList’ and store that in ‘reversedList’

[XavierPlatinum]

I want to reverse a list but want to store it in another list...

reverse the elements of the ‘myList’ and store that in ‘reversedList’

reversedList = mylist.reverse()

Now, if it is homework and you have to right a function to do this yourself, my hints would be:

#1  Using a negative indexes you can start at the end of the list and move backwards.
myList[-1] #the last item in the list
myList[-2] #the second to last item...  

# 2    Python's len() function tells you how many items in the list and therefor how times it needs to loop and copy the item to a new list.

[deanhystad]

reverse reverses the list in place and returns None.

x = list(range(10))
print(x.reverse())

Output:
None

To use reverse() to make a reversed copy you first need to make a copy of the list, then reverse the copy.

Read about reverse() here:
https://docs.python.org/3/tutorial/datas...e-on-lists

Or you might use the built-in slice() function.

Read about slice() here:
https://docs.python.org/3/library/functi...lice#slice

[SuperNinja3I3]

reversedList = mylist.reverse()

Now, if it is homework and you have to right a function to do this yourself, my hints would be:

#1  Using a negative indexes you can start at the end of the list and move backwards.
myList[-1] #the last item in the list

myList[-2] #the second to last item...  

# 2    Python's len() function tells you how many items in the list and therefor how times it needs to loop and copy the item to a new list.

wow I never knew this is that much easy lol thanks btw

[Pedroski55]

If you use .reverse() You don't see what's happening!

Better if you know what's going on, don't you think?

alphabet = 'abcdefghijklmnopqrstuvwxyz'

forward_list = [letter for letter in alphabet]

for i in range(len(alphabet)-1, -1, -1):
    print(alphabet[i])
    
backward_list = [alphabet[i] for i in range(len(alphabet)-1, -1, -1)]
# or
for i in range(-1, -(len(alphabet)+1), -1):
    print(alphabet[i])

backward_list = [alphabet[i] for i in range(-1, -(len(alphabet)  + 1), -1)]

[Yoriz]

This could be done by simply slicing the list.

items = [1, 5, 23, 67]
reversed_items_copy = items[::-1]
print(f'{items=}')
print(f'{reversed_items_copy=}')

Output:
items=[1, 5, 23, 67]
reversed_items_copy=[67, 23, 5, 1]

[DeaD_EyE]

The reverse() method on a list, does return None. It's an inline modification of the list.

my_list = [1, 2, 3]
my_list = my_list.reverse()

The last line does 3 things:

• my_list is reversed inline
  
• the reverse() method of my_list return None
  
• None is assigned to the name my_list
  
• The list, where the name my_list pointed before, disappears after the garbage collection
  

The problem here is a wrong assumption. list.sort and list.reverse are inline operations, which modifies the list itself and those operations return None.

If you want to sort or reverse an iterable, use sorted or reversed.
The sorted built-in function always returns a list.
The reversed function returns a reversed_iterator, which must be consumed by a list for example.

my_original_list = [1, 2, 3]

# all following lists do not modify my_original_list
# they are new lists
my_reversed_list_1 = list(reversed(my_original_list))
my_reversed_list_2 = my_original_list[::-1]


# sorting reverse
random_values = [44, 1, -10, 42, 1337, -5, -1, 10, 13, -27]

from_big_to_small = sorted(random_values, reverse=True)

# printing the id for each list object
# they are all different list objects in memory
print(id(my_original_list), id(my_reversed_list_1), id(my_reversed_list_2), sep="\n")

https://docs.python.org/3/library/functions.html#sorted
https://docs.python.org/3/library/functi...l#reversed
https://docs.python.org/3/howto/sorting.html