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Re: st: conditional "keep" statement

From   David Kantor <>
Subject   Re: st: conditional "keep" statement
Date   Mon, 12 Apr 2010 11:07:58 -0400

At 09:54 AM 4/12/2010, David Souther wrote:
I'm combining (append & merge) hundreds of files which contain
hundreds or thousands of variables each, and at each stage of the
merge/append, I'd like to variables only if they are in a list that I
The issue is that not all of these datasets contain all the variables
in this list.  So, if I create a macro of my list,

local myvars  a1 a2 a3 d1 d2 d3

and then specify,

keep `myvars'

in the loop for each combination of data, I get the error that some
variable doesn't exist when it's not in the dataset.  I tried getting
around this with the -capture- command,

cap keep `myvars'

and using -ds-

ds `myvars'
keep `r(varlist)'


ds `myvars', not
drop `r(varlist)'

and -ds- in combination with -capture- to no avail.   Any other ideas
(besides specifying the hundreds of variables to keep for each/every

I'm not sure what to do if you bump into limits of macros, but I wonder if you know about macrolists. This may be useful.

local myvars  a1 a2 a3 d1 d2 d3
localdatasetvars "`r(varlist)'"
local commonvars : list myvars & localdatasetvars

commonvars now contains the variable names common to the dataset and to myvars.

See -help macrolists-.


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