One advantage of using
egen newvar = group(oldvar) if oldvar != 0
replace newvar = 0 if newvar == .
is that it extends easily to assignment of value labels, e.g.
egen newvar = group(oldvar) if oldvar != 0, label
replace newvar = 0 if newvar == .
The subtracting 1 route extends only messily to having labels as well.
As sooner or later you are likely to want to see labelled output, this
is a notable detail.
Nick
[email protected]
Frank Gallo
Hi Nick & Tirthankar,
Thank you for the suggestions. Here is what I did, which solved my
problem:
egen newvar = group(oldvar)
recode newvar (18=0)
replace newvar = newvar - 1
On Aug 23, 2009, at 12:05 PM, Nick Cox wrote:
Alternatively,
egen newvar = group(oldvar) if oldvar != 0
replace newvar = 0 if newvar == .
This exploits the fact the -egen, group()- never yields 0 as a result.
Tirthankar Chakravarty
Well, in your case (non-negative values) it is easy. Simply subtract 1
from the -group-ed variable:
*******************
sysuse auto, clear
tab mpg
recode mpg (18=0) // change 18 to 0
egen new = group(mpg)
replace new = new - 1
tab new
*******************
On Sat, Aug 22, 2009 at 4:24 PM, Frank Gallo<[email protected]> wrote:
> So the syntax "egen newvar = group(oldvar)" achieves my goal for one
> variable. But for another variable, I have "0" values that I want to
> keep
> and do not include in the grouping. I tried adding the if qualifier
> [egen
> newvar = group(oldvar) if oldvar > 0] but this transformed the 0s to
> missing. I would greatly appreciate any suggestions. Thank you.
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