On Jan 24, 2008 5:32 AM, Jason Grout <[EMAIL PROTECTED]> wrote: > > > William Stein wrote: > > On Jan 23, 2008 4:34 PM, Jason Grout <[EMAIL PROTECTED]> wrote: > >> > >> [EMAIL PROTECTED] wrote: > >>> > >>> > >>> On Wed, 23 Jan 2008, William Stein wrote: > >>> > >>>> On Jan 23, 2008 4:12 PM, Jason Grout <[EMAIL PROTECTED]> wrote: > >>>>> Does anyone know the best way to partition a list into sublists of a > >>>>> specific length, similar to the Partition command in Mathematica? I'm > >>>>> thinking of something like: > >>>>> > >>>>> sage: partition([1,2,3,4],2) > >>>>> [[1,2],[3,4]] > >>>>> sage: partition([1,2,3,4,5],2,pad=0) > >>>>> [[1,2],[3,4],[5,0]] > >>>>> > >>>>> It seems like this is a problem that python would have solved millions > >>>>> of years ago, but I can't find anything when searching online. I can > >>>>> whip it up quickly, but I'm sure it's already been invented, which is > >>>>> why I'm asking. > >>>> Let me be the first of many to post a one liner: > >>>> > >>>> sage: def partition(v, n): > >>>> ... return [v[n*i:n*i+n] for i in range(len(v)//n)] > >>>> > >>>> sage: partition([1,2,3,4],2) > >>>> [[1, 2], [3, 4]] > >>> Let me be the first of many to post a counterexample: > >>> sage: partition([1,2,3,4,5],2) > >>> [[1, 2], [3, 4]] > >>> > >>> and a fix: > >>> > >>> sage: def partition(v,n): > >>> ... return [v[i:i+n] for i in range(0,len(v),n)] > >>> sage: partition([1,2,3,4,5],2) > >>> [[1, 2], [3, 4], [5]] > >> And let me be the first of many to say that that was the solution that I > >> finally found as I continued to search. Is there a nice, fast function > >> that provides some of the pretty extensive functionality of the > >> Partition function in Mathematica? Or how about even just a default > >> padding, as in my example? > >> > >> See http://reference.wolfram.com/mathematica/ref/Partition.html > >> > >> > >> Or is it time to write such a function? :) > >> > >> As it is, the one-liner above is all I need for now. > > > > Thanks. I would actually strongly encourage you or somebody to > > sit down and actually write a function that has the _same_ functionality > > as http://reference.wolfram.com/mathematica/ref/Partition.html > > since that looks like a very useful function, and I think having it > > trivially available in Sage will be very useful to people used to > > Mathematica or people porting Mathematica code to Sage. > > I hope people will implement something with the same interface and > > submit a patch. > > trac #1909 > > Any suggestions for a name? We already have a partition class that is > called when you type "partition" >
What about partition_sequence In Python the word "sequence" is I think supposed to refer to either a list or a tuple, and your function should apply to either. Your function could also support an iterator version, if the input is an iterator. -- William --~--~---------~--~----~------------~-------~--~----~ 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://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
