On Apr 1, 9:23 pm, John O'Hagan <resea...@johnohagan.com> wrote: > Despite being thoroughly acclimatised to zero-based indexing and having no > wish to change it, I'm starting to see the OP's point. > > Many of the arguments presented in this thread in favour of zero-based > indexing have rather been arguments for half-open intervals, which I don't > think are in dispute. We all want these to be true: > > foo[:n] is the first n items of the sequence foo > foo[:n] + foo[n:] == foo > len(foo[n:m]) == m-n > (foo[n:n]) is an empty sequence > etc. > > and they are true with 0-based indexing if we exclude the last number, or > equally with 1-based indexing if we exclude the first.
Unless I'm missing something, wouldn't that mean: range(0,10) -> [1,2,3,4,5,6,7,8,9,10] Even though it's theoretically just another way to line up the open interval, as practical matter it's going to be a lot more confusing. Of course you could exclude the last number with one-based indexing also, but that would be confusing too, since you would have to use something like range(1,len(x)+1) to iterate over the items of x. Given that, I'm going to disagree that a half-open interval is desirable in the case of one-based indexing. Furthermore, I know of no languages that use both one-based indexing and half-open intervals. Do you know of any? > Beyond being part of a conventionally-ordered set of keys, what can an > ordinality of zero actually mean? (That's a sincere question.) I think people were being facetious. To me the first item in the list is x[0]--ordinal does not match cardinal. However, I don't use ordinals much when talking about list items; I'll say item 2, not third item. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
