I am relatively new to python and I am still trying to learn the basics of the language. I stumbled upon a question which asks you to rearrange the list by modifying the original. What you are supposed to do is move all the even index values to the front (in reverse order) followed by the odd index values.
Example:
l = [0, 1, 2, 3, 4, 5, 6]
l = [6, 4, 2, 0, 1, 3, 5]
My initial approach was to just use the following:
l = l[::-2] + l[1::2]
However, apparently this is considered 'creating a new list' rather than looping through the original list to modify it.
As such, I was hoping to get some ideas or hints as to how I should approach this particular question. I know that I can use a for loop or a while loop to cycle through the elements / index, but I don't know how to do a swap or anything else for that matter.
You can do it by assigning to a list slice instead of a variable:
l[:] = l[::2][::-1] + l[1::2]
Your expression for the reversed even elements was also wrong. Use l[::2] to get all the even numbers, then reverse that with [::-1].
This is effectively equivalent to:
templ = l[::2][::-1] + l[1::2]
for i in range(len(l)):
l[i] = templ[i]
The for loop modifies the original list in place.