James Stroud wrote: > I think that it would be handy for enumerate to behave as such: > > def enumerate(itrbl, start=0, step=1): > i = start > for it in itrbl: > yield (i, it) > i += step > > This allows much more flexibility than in the current enumerate, > tightens up code in many cases, and seems that it would break no > existing code. Yes, I have needed this behavior with enumerate, like > tonight and the current example. I put the "step" parameter in for > conceptual symmetry with slicing. > > Here is a case use (or is it use case?): > > > # with the proposed enumerate > import operator > def in_interval(test, bounds, first=1, reverse=False): > op = operator.gt if reverse else operator.lt # python 2.5 > bounds = sorted(bounds, reverse=reverse) > for i, bound in enumerate(bounds, first): > if op(test, bound): > return i > return i + 1 > > > # with the existing enumerate > import operator > def in_interval(test, bounds, first=1, reverse=False): > op = operator.gt if reverse else operator.lt # python 2.5 > bounds = sorted(bounds, reverse=reverse) > for i, bound in enumerate(bounds): > if op(test, bound): > return i + first > return i + first + 1 > > > py> # eg > ... > py> in_interval(8, bounds) > 2 > py> in_interval(1, bounds) > 1 > py> in_interval(1, bounds, reverse=True) > 5 > py> in_interval(8, bounds, reverse=True) > 4 > py> in_interval(20, bounds, reverse=True) > 2 > > Of course, I haven't used step here. Even in this trivial example the > proposed enumerate cleans the code and logic, eliminating a couple of > plus signs. For this real-world example, the practical requirement for > reversing the bins obfuscates somewhat the de-obfuscation provided by > the proposed enumerate. But I think that it might be obvious that the > proposed enumerate could help significantly in cases a bit more > complicated than this one. > > Any thoughts? > > James
After a brief reflection, I realized that I just described a "for-to-step-do" style loop one might find in many other languages, most notably BASIC. James -- http://mail.python.org/mailman/listinfo/python-list
