python print the last 40 elements of a list

Question

I am trying to do something pretty simple: I need to get the last 40 elements from a list.

I noticed that there is no direct way to do so, like you would do in a string, using one of the standard functions to get the last n chars from the string.

I know how to get the the length of the list; so what I had in mind is to just use the max lenght and do a for loop starting from the end of the list, and go backwards for 80 times.

max_size= len(my_list)

for i in range(max_size, (maxsize-80)):
    print my_list[i]
    i=i-1

Is this the correct way to do so? Or there is some sort of function in the list object that may do this? I tried the documentations of the python site but had no luck.

I see, so I just say print my_list[-40:] ? That's quite brilliant — , Feb 20 '13 at 00:54
@JBernardo that prints the items after the first 40, not the last 40 — wim, Feb 20 '13 at 00:56

score 2 · Accepted Answer · answered Feb 20 '13 at 00:54

2

my_list[-40:] contains the last 40 items. Specifically, a negative list index tells it to start counting that many items back from the end of the list, and the colon afterward tells it to continue until the end.

answered Feb 20 '13 at 00:54

octern

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score 1 · Answer 2 · answered Feb 20 '13 at 00:54

1

for i in my_list[-40:]:
    print(i)

answered Feb 20 '13 at 00:54

jurgenreza

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score 0 · Answer 3 · answered Feb 20 '13 at 01:09

0

Slicing is what you want as has been pointed out. You could if you only had an iterable (ie, you don't have a length / can only read forward):

>>> from collections import deque
>>> deque(range(10), 2)
deque([8, 9], maxlen=2)

answered Feb 20 '13 at 01:09

Jon Clements

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python print the last 40 elements of a list

3 Answers3