Bryan Olson wrote: > Steven Bethard wrote: > > Well, I couldn't find where the general semantics of a negative stride > > index are defined, but for sequences at least[1]: > > > > "The slice of s from i to j with step k is defined as the sequence of > > items with index x = i + n*k such that 0 <= n < (j-i)/k." > > > > This seems to contradict list behavior though. [...] > > The conclusion is inescapable: Python's handling of negative > subscripts is a wart.
I'm not sure I'd go that far. Note that my confusion above was the order of combination of points (3) and (5) on the page quoted above[1]. I think the problem is not the subscript handling so much as the documentation thereof. I posted a message about this [2], and a documentation patch based on that message [3]. [1] http://docs.python.org/lib/typesseq.html [2] http://mail.python.org/pipermail/python-list/2005-August/295260.html [3] http://www.python.org/sf/1265100 > Suppose instead of using semicolons as the PPEP proposes, we use > commas, as in: > > sequence[start, stop, step] This definitely won't work. This is already valid syntax, and is used heavily by the numarray/numeric folks. STeVe -- http://mail.python.org/mailman/listinfo/python-list
