st: RE: Looping gen sequentially over datasets

[Joe Canner <jcanner1@jhmi.edu>]

Alex,

You are probably right that a -foreach- loop will be required.  Can you provide some information on the naming convention for each file (i.e., what is similar and what is different) so that we can recommend the right solution?  In the meantime, here is a general solution:

. local id=0
. foreach file in "file1" "file2" ... {
.  use `file', clear
.  local ++id
.  gen School_ID=`id'
.  save , replace
. } 

If your only use for this is to have a unique identifier after you combine the data sets, also consider using the -gen(newvar)- option of the -append- command.  This can be used to identify which data set contributed to the conglomerated data set and you can use that to generate unique IDs after the append, instead of using the looping method above to add an identifier to each dataset.

Regards,
Joe Canner
Johns Hopkins University School of Medicine

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Alex Sutherland
Sent: Wednesday, September 25, 2013 12:27 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: Looping gen sequentially over datasets

Dear Statalisters,

I am trying to generate sequential ID variables over a series of datasets.
There are 40 datasets representing 40 schools and I want to generate an ID variable for each school (ranging from 1-40) without the need to open and edit each file manually. (I'm likely to have to repeat this process later and I want to combine the datasets once the ID variable is created, hence the need for unique identifiers for each school). I keep thinking it's going to involve a foreach loop over the datasets combined with another loop (forval?), but then I'm up against the limits of my Stata-ing so any help gratefully received.

Thanks in advance,

Alex

Dr. Alex Sutherland
Research Methods Associate,
Social Sciences' Research Methods Centre (SSRMC) http://www.ssrmc.group.cam.ac.uk/

Office 3.12
Institute of Criminology,
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Tel: +44 (0)1223 746519
as2140@cam.ac.uk
http://www.crim.cam.ac.uk/people/academic_research/alex_sutherland/

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