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Re: Sorting Rows of a Matrix

  • To: mathgroup at
  • Subject: [mg65119] Re: Sorting Rows of a Matrix
  • From: dh <dh at>
  • Date: Wed, 15 Mar 2006 06:28:35 -0500 (EST)
  • References: <dv69a6$o6l$>
  • Sender: owner-wri-mathgroup at

Hi Greg,
you can solve thhis problem by using the second argument of Sort (see 
the manual). E.g. r will choose the sorting row:

Sort[m, #1[[r]] < #2[[r]] &]

with r=2 we get: {{1, 3}, {2, 2}, {3, 1}}
with r=2 we get: {{3, 1}, {2, 2}, {1, 3}}


Gregory Lypny wrote:
> Hello everyone,
> How can I sort the rows of a matrix by using one or more of the  
> columns as sort keys just like in a spreadsheet?  For example, if  
> matrix M is 12 x 2 with numbers in the first column and unordered  
> month numbers in the second, how would I order the rows by month?
> 	Regards,
> 		Greg

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