st: RE: Dropping variables

[Zhiqiang Wang <z.wang@uq.edu.au>]

Try this: 

foreach var of varlist  soils* {
	sum `var'
 	if r(mean)==0 {
		drop `var' 
 	}
}

The -if- expression after -drop- is only for selecting a subset of
observations. 

Zhiqang Wang
Centre for Chronic Disease
School of Medicine 
The University of Queensland, Australia
 
From: Pradeep Kurukulasuriya [mailto:pradeep.kurukulasuriya@yale.edu] 
Sent: Thursday, 4 November 2004 1:42 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: Dropping variables

I have  a large dataset with a lot of variables. I am trying to get rid of a
subset of the variables subject to a IF condition. I thought of  doing this
in a loop such as the following:

foreach var of varlist soils*{
sum `var'
drop `var' if r(mean)==0
}

However, the above doesn't work because stata doesn't like line 3. Is there
a way around this or another way to get rid of particular variables subject
to an IF condition?

Thanks
Pradeep





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