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RE: st: Looping across variables in variable columns
Sorry this should have been egen -rowtotal-. No mystery.
I still would have liked to figure out how to pass variables to -rowtotal- which would have made my task easier.
Below is part of what I tried given that variables -age- and - year- are known. Sorry it may be too basic stata for most people and I prefer readable long code!.
generate yr16 = year - age + 16
generate yr18 = yr16 + 2
tostring startyr, generate(yr16)
tostring stopyr, generate(yr18)
generate startpos = "sehead" + startyr if (yr16>=1968)
generate stoppos = "sehead" + stopyr if (yr18<=2005)
generate timespan = "("+startpos + " - " + stoppos+")"
egen prsemp = rowtotal(sehead1968 sehead1969 sehead1970)
Edward
________________________________
From: [email protected] on behalf of Nick Cox
Sent: Fri 4/27/2007 10:09 AM
To: [email protected]
Subject: RE: st: Looping across variables in variable columns
Glad you were helped by the responses.
Meanwhile, the mystery of what -rowcount- is remains.
Nick
[email protected]
Mungai, Edward
> Thank you all who gave ideas on this querry.
>
> Being new to stata I have chosen and managed to implement
> solution 1B and taken into consideration other comments
> relating to missing values. I am motivated to learn more stata!.
n j cox
> I can't find -rowcount- using -findit- or Google. Recall the
> precept in
> the Statalist FAQ:
>
> "Say what command(s) you are using. If they are not part of official
> Stata, say where they come from: the STB/SJ, SSC, or other archives."
>
> That said, this is a nice problem. It has got enough spin (cricket
> sense, not public relations!) to be interesting, yet yields
> to a little knowledge of Stata.
...
Mungai, Edward <[email protected]>
> I have seen discussions on looping across an unknown number of columns
> which can be solved by -reshape-.
>
> My question is how to sum across columns where the number of columns
> varies from one observation to the next. i.e. I may need to
> sum columns
> 2 to 5 for the first observation but from columns 4 to 11 for the
> second observation. In all cases the summation is done across a set of
> adjacent columns.
>
> I have tried to use -rowcount-, and the looping functions
> but as far as
> I can tell all sum across a fixed number of columns from one
> observation
> to the next. But there is something good also; the information on the
> column to begin and the column to end the summation for each
> observation is contained in two adjacent column which are
> the same for
> all the observations.
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