Re: st: drop range of variables meeting condition in another variable

["Tamer Farag" <tfarag@medicine.umaryland.edu>]

Many thanks, Nick.  I downloaded and installed findname.  However,  I am actually trying to apply two conditions, but it seems findname only applies 1.  I need to do the following:
 
1.  All of the gene variables have a value of 0, and 
2.  case==1
 
Is there a way to do the above?  
 
Also, I was not able to get the second part to work.  When I type: 
 
drop 'r(gene*)', I get an r(101) error "factor variables and time-series operators not allowed".  
 
When I alternatively try:
 
drop 'r(gene1-gene14000)', I get an r(100) error "varlist or in range required"
 
What am I doing wrong? 
 
Many thanks again,
Tamer
 
>>> Nick Cox <njcoxstata@gmail.com> 3/18/2013 4:26 PM >>>
Last line should be

drop `todrop'

Nick

On Mon, Mar 18, 2013 at 8:02 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> At a guess, you want to -drop- all gene variables that are identically
> zero. That is
>
> findname gene*, all(@==0)
>
> drop `r(varlist)'
>
> where -findname- is to be found by -search findname- and downloaded
> from the Stata Journal files.
>
> It is not so difficult without -findname-, either.
>
> foreach v of var gene* {
>        su `v', meanonly
>        if r(max) == 0 local todrop `todrop' `v'
> }
> drop `v'
>
> Nick
>
> On Mon, Mar 18, 2013 at 7:53 PM, Tamer Farag
> <tfarag@medicine.umaryland.edu> wrote:
>
>> I am working with a case control dataset with gene clusters variables.  I have approx 100 observations, a handful of essential variables, but approx. 14,000 variables for each observation that represent gene clusters (absent/present, 0/1).  The gene variables are all located next to each other in the dataset (i.e., gene1-gene14000).
>>
>> I would like to drop variables for gene clusters that are not present among my cases.  Obviously, specifying each gene cluster variable would be impractical.
>>
>> Is there any way to do this in Stata?  I'm stumped.

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