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Re: Multi-column sort [message #79497 is a reply to message #79404]

Thu, 01 March 2012 14:02

wlandsman
Messages: 743
Registered: June 2000

Senior Member

You might look at Craig Markwardt's multisort

http://cow.physics.wisc.edu/~craigm/idl/down/multisort.pro

On Thursday, March 1, 2012 10:02:06 AM UTC-5, Percy Pugwash wrote:
> I would like to sort a 2D string by column, specifying primary,
> secondary and further sort criteria (i.e. rows which are equal based
> on criterion 1 are sorted by criterion 2).
>
> Is there any neat way to do this in IDL?
>
> I'd thought of using the following:
>
> tosort = [3,1,5] ; Sort by column 3, then 1, then 5
> maxlen = max(strlen(sortarray[tosort,*])) ; Length of longest string
> paddedarray =
> string(sortarray[tosort,*],format='(a'+string(maxlen,format= '(i0)') +
> ')' ) ; Pad all strings to match longest length
> concatarray = paddedarray[0,*]
> for i = 0, n_elements(tosort)-1 do concatarray += paddedarray[i,*] ;
> Concatenate strings across columns
> indices = sort(concatarray) ; Sort the concatenated strings
>
> However, this method does not allow me to specify which direction the
> sort should go for each of the sort columns. Can anyone think of a way
> to extend the method to allow this (or a completely different method
> which achieves the same effect!)?
>
> Thanks,
>
> P

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[Message index]

		Multi-column sort By: Percy Pugwash on Thu, 01 March 2012 07:02
		Re: Multi-column sort By: Percy Pugwash on Mon, 05 March 2012 02:59
		Re: Multi-column sort By: Brian Wolven on Mon, 05 March 2012 09:54
		Re: Multi-column sort By: Percy Pugwash on Mon, 05 March 2012 02:53
		Multi-column sort By: cgguido on Fri, 02 March 2012 04:26
		Re: Multi-column sort By: wlandsman on Thu, 01 March 2012 14:02

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