Date:         Mon, 1 Oct 2001 12:36:44 -0700
Reply-To:     Dale McLerran <dmclerra@MY-DEJA.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Dale McLerran <dmclerra@MY-DEJA.COM>
Subject:      Re: SAS/IML manipulating subscripts
Comments: To: philippe.guiblin@ons.gov.uk
Content-Type: text/plain

Philippe,

Here is a little program which demonstrates one method of selecting
a subset.  There are other ways, and I do not claim that the method
demonstrated is in any way optimal.

proc iml;
  /* generate a vector to sample from */
    x = (1:5)`;

  /* determine size of vector */
    N = nrow(x);

  /* nonzero values of vector VECUSE are rows to be selected */
    vecuse = (1:n)`#(x^=3);

  /* Sort VECUSE returns nonselected (0) values at front */
    cvecuse = vecuse;
    vecuse[rank(vecuse),] = cvecuse;

  /* determine start value of first nonzero element */
    begin = sum(vecuse=0) + 1;

  /* Get subset of X using nonzero subset of vecuse */
    xsubset = x[vecuse[begin:n,],];
    print xsubset;
quit;


Alternatively, you could count the number of observations in your
matrix or vector which should go into the subset, initialize the
subset matrix or vector using the J function, and loop over the
original matrix filling in the next row of the subset matrix if
the row of the original matrix is not to be excluded.

Dale

>Date:         Mon, 1 Oct 2001 17:04:07 +0100
>Reply-To: Philippe.Guiblin@ONS.GOV.UK
> Philippe Guiblin <Philippe.Guiblin@ONS.GOV.UK>      SAS/IML manipulating subscripts SAS-L@LISTSERV.UGA.EDU
>Dear all,
>
>does anyone know how within SAS/IML I can delete observations.
>For example within a data set "dat" containing the variable v1, v2, v3, I
>would like to delete
>the observations corresponding to the values of v3 equal to 3.
>
>Thanks for your help.
>
>Philippe
>
>
>
>
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---------------------------------------
Dale McLerran
Fred Hutchinson Cancer Research Center
mailto: dmclerra@fhcrc.org
Ph:  (206) 667-2926
Fax: (206) 667-5977
---------------------------------------

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