"Charles Cuell" <[EMAIL PROTECTED]> wrote > The one odd thing about Python's slice notation is that the -1 means > to > start from the end and work backwards. My first inclination would > have > been to assume that -1 means to start at i and go to j by steps > of -1 > (only nonempy if j < i).
I mentally resolve this by thinking of sequences as being circular. Thus the -1 character is the last one - the one before the first. But that doesn't work for the step size k, you just have to realise that the minus sign there means work backwards and therefore start from the second parameter. However... >>> 'abcdefgh'[3:1:-1] 'dc' >>> 'abcdefgh'[1:3:-1] '' >>> 'abcdefgh'[::-1] 'hgfedcba' It seems that if you do provide values for j,k the first must be bigger than the second to work so Python is being slightly more intelligent about the default values than I initially thought, but the docs do say: ---------------- If i or j are omitted or None, they become ``end'' values (which end depends on the sign of k). --------------- How interesting. And thank goodness for the >>> prompt. - the ultimate arbiter and test... Alan G. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
