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" Jason --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
