So, what if you were to omit the first index? In that case, it will start at the beginning and go up to but not include that index. And if you were to omit both indexes, it’s going to return a copy of the entire list.Ġ3:54 And unlike with a string, it’s a copy-not a reference to the same object. If you omit the last index, it’s going to extend the slice from the first index and go all the way to the end of the list. By omitting the first index, your slice is going to start at the beginning of the list and go up to the second index. From 2 up to but not including 5.Ġ3:05 Great! You can also use negative indexes, so you could say starting at -5 and going to -2, which is the same as going from 1 to 4.Ġ3:29 A shorthand is available. What if you wanted to slice? Let me have you start at index 2 and then using a colon. So in this example, if a is your list, then inside your square brackets you would have your two index numbers separated by a colon ( :), and it’s going to return a portion of that a list that will start with position m and go up to but not include index n.Ġ2:38 Using that same example from before, if you took a, you’d get the three objects in the middle, starting at index 2 and going up to index 4, but not including 5.Ġ2:50 Let me have you try it out. Slicing’s an indexing syntax that’s going to extract a portion from your list. So in this case -6-which is also negative the length of your list-would return the first item.Ġ2:05 If you try to access an index that’s beyond the scope, you’ll get that index out of range also. So continuing to work with that list a I’ll have you try out negative indexing.Ġ1:44 a will access the last item, a, and so forth. Negative indexing is available also.Ġ1:33 If you want to access the last item, you’d start with -1. Another way to get there would be a and the len() (length) of a minus 1.Ġ1:18 If you use an index value that’s too high, Python will raise an exception- an Inde圎rror saying that the list index is out of range. And in this case, a would access the last.
As described, indexes are zero-based for lists, so a would access the first item in that list.Ġ1:03 a would access the third one. So if you have a list such as this, with these six elements, the indices start with 0 and would go up to 5.Ġ0:36 Let me have you try that out. To do that, you name the list, and then inside of a pair of square brackets you use an index number, like what I’m showing right here.Ġ0:17 That allows access to individual elements within the list.
The elements of a list can be accessed by an index. 00:00 In this video, you’ll practice list indexing and slicing.
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