RE: st: construct a loop

[Nick Cox <n.j.cox@durham.ac.uk>]

The help for -egen, group()- tells you about its -label- option. You really could have looked at that first! 

foreach v in var1 var2 var3 { 
	egen group=group(`v')
	sum group, meanonly
	forval i = 1/`r(max)' {
		di "`v': `: label (group) `i''" 
		stmh hivstatus if group ==`i'
	}
	drop group 
} 

is my guess at the other question. See -help extended_fcn- for the -label- stuff. 

Nick 
n.j.cox@durham.ac.uk 

Nikolaos Pandis

Dear Nick,

Thank you. 

********************
egen group=group(age_cat gender)

sum group  ,meanonly

foreach i of num 1/`r(max)' {
stmh hivstatus if group ==`i'
}
**************************


I have added another variable and I get 6 combinations since age_cat has 3 levels (0,1,2) and gender 2 (0,1). 
Should I assume that the sequence of the combinations is:
age_cat:gender 00 01 10 11 20 21? 
Could we label them?

Also, what if I do not want the combinations but rather to run the same code below for a number of variables separately.  

********************
egen group=group(var1)

sum group  ,meanonly

foreach i of num 1/`r(max)' {
stmh hivstatus if group ==`i'
}

egen group=group(var2)

sum group  ,meanonly

foreach i of num 1/`r(max)' {
stmh hivstatus if group ==`i'
}


egen group=group(var3)

sum group  ,meanonly

foreach i of num 1/`r(max)' {
stmh hivstatus if group ==`i'
}

ect
**************************
How would I be able to consolidate the above 3 pieces of code into 1?

Many thanks,

Nick


--- On Mon, 2/21/11, Nick Cox <n.j.cox@durham.ac.uk> wrote:

> From: Nick Cox <n.j.cox@durham.ac.uk>
> Subject: RE: st: construct a loop
> To: "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
> Date: Monday, February 21, 2011, 8:12 PM
> This too is covered in the FAQ just
> cited. 
> 
> "It extends easily to the apparently much more difficult
> problem of going through all the distinct combinations of
> two or more variables, which is, in fact, only a little more
> difficult. 
>     . egen group = group(varlist)
> 
> Now the code is exactly the same as before. That is,
> instead of one varname, you just need to spell out a varlist
> in the argument to egen."
> 
> Nick 
> n.j.cox@durham.ac.uk
> 
> 
> Nikolaos Pandis
> 
> 
> Thank you. I came up with the following code:
> 
> *********************
> egen group=group(age_cat)
> 
> sum group  ,meanonly
> 
> foreach i of num 1/`r(max)' {
>  stmh hivstatus if group ==`i'
> }
> ****************
> 
> How could I make this to do the same thing for other
> variables such as age_cat?
> 
> 
> --- On Sun, 2/20/11, Nick Cox <njcoxstata@gmail.com>
> wrote:
> 
> > Well, your solution then gets more
> > complicated. The thread has already
> > shown that you can nest loops. Also see
> > 
> > FAQ     . . . . . . . . . . Making
> > foreach go through all values of a variable
> >         . . . . . . . . . . . . . . . .
> > . . . . . . . . . . . . . .  N. J. Cox
> >         8/05    Is there a
> > way to tell Stata to try all values of a
> >                
> > particular variable in a foreach statement without
> >                
> > specifying them?
> >                 http://www.stata.com/support/faqs/data/foreach.html
> > 
>  
> > On Sat, Feb 19, 2011 at 8:48 PM, Nikolaos Pandis
> <npandis@yahoo.com>
> > wrote:
> > 
> > > Thank you all this looks great!
> > >
> > > Now what if I would like to run the same commands
> for
> > more than just the varX variable?
> > > What if the variables have variable number of
> category
> > levels?
> > >
> > > Many thanks,
> > >
> > > Nick
> > >
> > >
> > >
> > > --- On Sat, 2/19/11, Nick Cox <njcoxstata@gmail.com>
> > wrote:
> > >
> > >> From: Nick Cox <njcoxstata@gmail.com>
> > >> Subject: Re: st: construct a loop
> > >> To: statalist@hsphsun2.harvard.edu
> > >> Date: Saturday, February 19, 2011, 9:14 PM
> > >> Here is another way to do it.
> > >>
> > >> foreach p in "1 0" "2 0" "3 0" "2 1" "3 1" "3
> 2"
> > {
> > >> tokenize "`p'"
> > >> stmh varX, c(`1' , `2')
> > >> }
> > >>
> > >> Nick
> > >>
> > >> On Sat, Feb 19, 2011 at 12:03 PM, Nikolaos
> Pandis
> > <npandis@yahoo.com>
> > >> wrote:
> > >>
> > >> > I would like to run the following
> commands
> > using the 4
> > >> level varX:
> > >> > stmh varX,c(1,0)
> > >> > stmh varX,c(2,0)
> > >> > stmh varX,c(3,0)
> > >> > stmh varX,c(2,1)
> > >> > stmh varX,c(3,1)
> > >> > stmh varx,c(3,2)
> > >> >
> > >> > I would grateful if someone would help
> me
> > construct a
> > >> loop to run all the above commands.

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