st: combine data by groups

["G. Dai" <dgecon@gmail.com>]

hi all, this is an easy question,but somehow I can't figure it.
The data is like:
personid     parentsid              momlive                   dadlive
001                   1                      0
 .
001                   2                      .
  1
002                   1                      1
 .
002                   2                        .
   1

where personid and parentsid  are person and her parents' id.
when parentid==1, we only record whether mom still live or not (momliv)
similarly
for parentid==2 and dadlive.

I want to change the data set to the following form

personid         momlive                   dadlive
001                  0                              1
002                   1                              1

what is the best way to do this?

thanks,
Guang

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