topic selecting columns using an index like in R? in SAS Procedures

selecting columns using an index like in R?

flh3 — Fri, 20 Feb 2015 17:49:04 GMT

Is it possible to select/keep columns in SAS by using an index like in R? (e.g., I want to keep columns 2 through 5 in a dataset with 10 variables). I want to do this without specifying the names (e.g., keep x1 x2 x3).

In R, to see only those columns (without knowing the column names), I would type x[,2:5]

Re: selecting columns using an index like in R?

art297 — Fri, 20 Feb 2015 17:58:41 GMT

You could use proc sql to create a macro variable. e.g.:

proc sql;

select name

into :vars separated by ' '

from dictionary.columns

where libname="SASHELP" and /*must be upper case*/

memname="CLASS" and /*must be upper case*/

varnum between 2 and 5

;

quit;

data want;

set sashelp.class (keep=&vars.);

run;

Re: selecting columns using an index like in R?

Rick_SAS — Fri, 20 Feb 2015 18:16:25 GMT

An interesting question. If you know the 2nd and 5th names, you can use the -- operator to get the variable names between them. I didn't know how to do the general case, but I found a useful paper by Stephanie Thompson that describes how to use PROC SQL to do this operation: http://analytics.ncsu.edu/sesug/2006/CC01_06.PDF

Here is one solution:

proc contents data = Sashelp.Cars noprint out=vars(keep = varnum name);
run;

proc sql noprint;
   select name
   into :keepvars separated by ' '
   from vars
   where 2 <= varnum <= 5
   order by varnum;
quit;

%put &keepvars;

data subset;
set Sashelp.Cars;
keep &keepvars;
run;

Re: selecting columns using an index like in R?

flh3 — Mon, 23 Feb 2015 21:39:01 GMT

Thanks Art and Rick for the answers! Both solutions work (I was hoping for a solution that didn't use SQL but that's fine).

Re: selecting columns using an index like in R?

Tom — Mon, 23 Feb 2015 23:20:06 GMT

If you want to treat a series of variables as if they form a matrix then why not just name them using numeric suffixes? Such X1-X10. Then it is as easy to select as typing in the index numbers. You can use the LABELS to store more meaning information about the variables.

Re: selecting columns using an index like in R?

Jagadishkatam — Tue, 24 Feb 2015 00:58:50 GMT

Hi ,

Here is an approach of getting the desired output but from datastep without the use of proc sql.

data class;

set sashelp.class;

run;

data columns;

set sashelp.vcolumn;

where libname='WORK' and memname='CLASS' and 2<=varnum<=5;

call symputx("keep"||trim(put(varnum,1.)),name);

run;

%put &keep2 &keep3;

%macro vars;

data class1;

set class;

keep %do j=2 %to 5; &&keep&j %end;;

run;

%mend;

%vars

hope it helps.

Thanks,

Jag