On Sep 21, 2007, at 5:40 AM, Jaap Spies wrote: > William, > > I'm sorry to see that irange is not in sage-2.8.5. > > Your comment: > >> I think http://trac.sagemath.org/sage_trac/ticket/702 is actually >> much nicer to use, so for now I think irange isn't needed. > > is not quite to the point. > > irange can take three arguments: start, stop and step. > The arguments are not restricted to integers.
So can the other range functions we have. > See the examples I give. Moreover I think irange is more Pythonic! I think the fact that irange looks so much like range is actually a disadvantage because they act so different (I consider potentially returning an extra item a significant difference, especially since the presence of that extra item is sensitively dependent on (end- start) % step.) I would be in favor of shortening srange(..., include_endpoint=True) to srange(endpoint=True). In trying out your examples, I realized a shortcoming with the new notation though. First, sometimes it's more convenient to give a step rather than a second item. What would people think about the notation [start .. end ; step] Also, [10..1] now returns [10], it should probably return the empty list. What about [10,11,.,0]? Also the empty list? I think so. Thoughts? > As irange is based only on srange it will be fast now tick #701 is > closed. > > Arguments enough to reopen ticket #706, I think. I don't think so, especially after resolving the issues above, but the two of us are probably equally bias about or own pieces of code. The only other person to have spoken up is William, maybe we should consider re-opening it if others speak up. - Robert Examples: >> sage: v = irange(0,5); v >> [0, 1, 2, 3, 4, 5] sage: v = [0..5]; v [0, 1, 2, 3, 4, 5] >> sage: v = irange(1,10); v >> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] sage: v = [1..10]; v [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] >> sage: v = irange(10,-1,-1); v >> [10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, -1] sage: v = [10,9,..,-1]; v [10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, -1] > >> sage: v = irange(1,8, 1/2); v >> [1, 3/2, 2, 5/2, 3, 7/2, 4, 9/2, 5, 11/2, 6, 13/2, 7, 15/2, 8] sage: v = [1, 3/2, .., 8]; v [1, 3/2, 2, 5/2, 3, 7/2, 4, 9/2, 5, 11/2, 6, 13/2, 7, 15/2, 8] >> sage: v = irange(1,2, 0.4); v >> [1, 1.40000000000000, 1.80000000000000] sage: v = [1,1.4,..,2]; v [1.00000000000000, 1.40000000000000, 1.80000000000000] >> sage: v = irange(1, 2, 0.5); v >> [1, 1.50000000000000, 2] sage: v = [1,1.5,..,2]; v [1.00000000000000, 1.50000000000000, 2.00000000000000] >> sage: v = irange(1, 2, -0.5); v >> [] sage: v = [1,.5,..,2]; v # this is different because it computes the range 0.5 to 2 (with step -0.5) after appending the first items to the list. Bug? [1.00000000000000, 0.500000000000000] >> sage: v = irange(2, -2, -0.5); v >> [2, 1.50000000000000, 1.00000000000000, 0.500000000000000, >> 0.000000000000000, -0.500000000000000, -1.00000000000000, >> -1.50000000000000, -2] sage: [2,1.5,..,-1.5] [2, 1.50000000000000, 1.00000000000000, 0.500000000000000, 0.000000000000000, -0.500000000000000, -1.00000000000000, -1.50000000000000, -2] >> sage: v = irange(10,1); v >> [] sage: [10,..,1] [10] >> sage: v = irange(10,10); v >> [10] >> sage: v = irange(10); v >> Traceback (most recent call last): >> ... >> TypeError: irange() takes at least 2 arguments (1 given) >> sage: v = irange(0.5, 2.5, 0.5); v >> [0.500000000000000, 1.00000000000000, 1.50000000000000, >> 2.00000000000000, 2.50000000000000] sage: [0.5,1,..,2.5] [0.500000000000000, 1.00000000000000, 1.50000000000000, 2.00000000000000, 2.50000000000000] >> sage: [n^2 for n in irange(-1, 10)] >> [1, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100] sage: [n^2 for n in [-1..10]] [1, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100] sage: [n^2 for n in (-1..10)] # as a generator [1, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100] >> And this one from the calculus thread! >>> -- I think that the Python convention of not including the upper >>> bound >>>>> in a sum is a real problem. >>>>> >>>>> sage: sum(i for i in range(1,10)) >>>>> 45 >>>>> >>>>> I understand this is a fundamental convention in Python, and >>>>> that it is >>>>> very >>>>> natural for people used to malloc(), but I worry that this will >>>>> be a >>>>> constant >>>>> headache for students (and professors!). >> >> >> sage: sum(i for i in irange(1, 10)) >> 55 sage: sum(1..10) 55 --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
