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Re: Partition a list based on columns

  • To: mathgroup at smc.vnet.net
  • Subject: [mg119699] Re: Partition a list based on columns
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Fri, 17 Jun 2011 05:52:47 -0400 (EDT)
  • References: <itcdai$d13$1@smc.vnet.net> <201106170406.AAA28684@smc.vnet.net>
  • Reply-to: drmajorbob at yahoo.com

How about

Clear[m, n]
m[x_List] := Module[{n = Sqrt@Length@x},
   Normal@SparseArray[
      Rule @@@
       Transpose@{SortBy[Flatten[Array[List, {n, n}], 1], Total], x}] /;
     IntegerQ@n
   ]
m[Range@9] // MatrixForm

(* suppressed *)

m[Range@16] // MatrixForm

(* suppressed *)

m[Range@7]

m[{1, 2, 3, 4, 5, 6, 7}]

Bobby

On Thu, 16 Jun 2011 23:06:31 -0500, Ray Koopman <koopman at sfu.ca> wrote:

> On Jun 16, 1:02 am, StatsMath <stats.ma... at gmail.com> wrote:
>> [...]
>>
>> What would be a good way to line up elements in a list in a diagonal
>> fashion, for ex: from Range[9] want to create the follwing matrix:
>>
>> 1 2 4
>> 3 5 7
>> 6 8 9
>
> This is better than my previous suggestion:
>
> m[n_] := Partition[FoldList[Plus,0,Join[Range[n-1],Range[n-1,1,-1]]],
>                    n, 1] + Range[n]
>


-- 
DrMajorBob at yahoo.com


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