```Date: Tue, 29 Jul 2003 19:36:11 -0400 Reply-To: Jonathan Siegel Sender: "SAS(r) Discussion" From: Jonathan Siegel Subject: Re: array processing Comments: To: Dale McLerran As Dale points out, arrays aren't really what you want here. They make the solution more complicated than it needs to be. Jonathan Siegel On Tue, 29 Jul 2003 11:46:03 -0700, Dale McLerran wrote: >A simple datastep approach that works similarly to Prasad's SQL >solution would be as follows: > >data two; > set one(keep=vara rename=(vara=newvar)) > one(keep=varb rename=(varb=newvar)) > one(keep=varc rename=(varc=newvar)); >run; > > >An array based solution would have to load all of the data into >memory in a two dimensional array which is indexed on variable >and row number. When all data have been read, then loop back >through the data by row number within variable index. Thus, >we could write the following: > >data two; > set one end=lastrec; > array var_in {3} vara varb varc; > array all_dat {3,10000} _temporary_; > > /* Store observed values into _n_th row of all_dat array */ > do i=1 to 3; > all_dat{i,_n_}=var_in{i}; > end; > > /* Once we have read all the data, then loop over rows */ > /* within variable indexes and write the stored value. */ > if lastrec then do; > do i=1 to 3; > do j=1 to _n_; > newvar = all_dat{i,j}; > output; > end; > end; > end; > keep newvar; >run; > > >Hope these help, > >Dale > > >--- Prasad S Ravi wrote: >> Carey: >> >> If your friend does not care for a PROC SQL solution which may be >> less >> efficient than the array solutions >> here is another way, assuming the TYPE and LENGTH of the variables >> are the >> same: >> >> data one; >> vara=1; >> varb=2; >> varc=3; >> run; >> >> proc sql; >> create table two as >> select vara as newvar >> from one >> union >> select varb as newvar >> from one >> union >> select varc as newvar >> from one; >> quit; >> run; >> proc print data=two; >> run; >> >> output: >> >> Obs newvar >> 1 1 >> 2 2 >> 3 3 >> >> >> Prasad Ravi >> >> >> >> >> >> >> Carey Smoak >> > SAS-L@LISTSERV.UGA.EDU >> M> cc: >> Sent by: "SAS(r) Subject: array >> processing >> Discussion" >> > DU> >> >> >> 07/29/2003 09:34 AM >> Please respond to >> Carey Smoak >> >> >> >> >> >> >> Hi SAS-Lers, >> >> I am submitting this question for a co-worker of mine. >> >> Suppose you have a dataset that has 10,000 observations and three >> variable (VarA, VarB and VarC). Suppose that you want to create a >> new >> dataset with a single variable that appends VarB and then VarC to >> VarA. This new dataset would have 30,000 observations. Is there a >> way to use array processing to accomplish this task? My co-worker >> has >> made several attempts at using arrays, but has not been successful. >> >> Of course, this can be done with several data steps, but my co-worker >> is trying to find a more efficient solution using arrays. >> >> Regards, >> >> Carey G. Smoak >> Roche Molecular Systems, Inc. > > >===== >--------------------------------------- >Dale McLerran >Fred Hutchinson Cancer Research Center >mailto: dmclerra@fhcrc.org >Ph: (206) 667-2926 >Fax: (206) 667-5977 >--------------------------------------- > >__________________________________ >Do you Yahoo!? >Yahoo! SiteBuilder - Free, easy-to-use web site design software >http://sitebuilder.yahoo.com ```

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