Re: st: generate variable equal to first non-zero value in row

[Nick Cox <njcoxstata@gmail.com>]

How would you do it by hand? You would look at each variable from left
to right until you find the first non-zero. So, Stata can be
instructed to do that too.

gen first_nonzero = .

qui forval j = 1/5 {
       replace first_nonzero = `j' if out`j'  & first_nonzero == .
}

Note here that

if `outj'

is short-hand for

if `outj' != 0

and we also need the condition that

first_nonzero == .

If all values are zero, the variable remains set to missing.

For a fairly detailed review of such questions, see

SJ-9-1  pr0046  . . . . . . . . . . . . . . . . . . .  Speaking Stata: Rowwise
        (help rowsort, rowranks if installed) . . . . . . . . . . .  N. J. Cox
        Q1/09   SJ 9(1):137--157
        shows how to exploit functions, egen functions, and Mata
        for working rowwise; rowsort and rowranks are introduced

which is accessible at http://www.stata-journal.com/sjpdf.html?articlenum=pr0046
Nick
njcoxstata@gmail.com


On 21 August 2013 16:25, D-Ta <altruist81@gmx.de> wrote:
> Dear Statausers,
>
> I have a dataset with the variables id and and out1-out5 where the "out"
> variables represent sequential outcomes. I would like to generate a variable
> (in the example below named first_nonzero) which indicates the first outcome
> in the sequence row that is non zero. If there are all zeros throughout,
> that indicator variable should be set/remain missing.
>
> The following table illustrateswhat I am trying to do. How do I generate the
> first_nonzero variable? (I was trying to work with the -egenmore- commands,
> but couldnt figure out).
>
> id      out1    out2    out3    out4    out5    first_nonzero
> 1       0       0       0       2       2       2
> 2       0       2       2       0       0       2
> 3       0       0       0       0       0                             .
> 4       4       4       4       0       0       4
> 5       3       0       2       2       2       3
> 6       0       4       4       4       0       4
>
>
> Many thanks,
> Darjusch
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