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. -- 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 -~----------~----~----~----~------~----~------~--~---
