In addition to good advice from Martin Weiss and Eva Poen:
There is a reference in this program draft to a local macro `varlist-reference' which is never defined. You'd find also that that - is not acceptable as a character in a macro name.
I would not write a program for the example problem, even with a need to apply this to multiple variables and a panel or similar structure.
Given a -touse- flagging which observations to use, an identifier -id- and a time variable -timevar-. The basic recipe is
foreach v of var <varlist> {
bysort touse id (timevar) : replace `v' = `v'[_n-1] if missing(`v')
}
Any further -if- conditions can be combined as usual. So, rather than putting that in a program, I would just use that (kind of) code directly.
On your more general point, I think you're confused on how to write byable programs. The main point is that -by:- takes care of most such details for you. Typically, you don't need to reproduce such control within a program.
If further study of the documentation does not make this clear, perhaps you need to specify either another example problem (because this one doesn't call for a program) or another sample program that would actually work.
Nick
[email protected]
Steinar Fossedal
I'm having trouble capturing the parameters for bysort used when
calling a program. The following simple (and untested) program
illustrates the problem. It replaces missing values with the
previously known value, using only a subset of the data.
capture program drop missing_like_last
program missing_like_last, byable(onecall)
syntax varlist [if]
marksample touse
bysort `touse' `_byvars' (`varlist2-reference'): replace `var' =
`var'[_n-1] if `var'==. & `touse'
end
bysort id (sortvar): missing_like_last myvar if somevar==1
(syntax for bysort is: bysort varlist1 (varlist2): ...)
As you can see, I'm trying to issue commands using the exact same
bysort-parameters as used when calling the program, just adding the
`touse' variable. I need the order to be correct as I am issuing
commands with references between rows ( [_n-1] ).
To do this, I need to capture the -bysort- parameters varlist1 and
varlist2 containing the values id and sortvar. -_byvars- takes care of
varlist1, but how can I capture varlist2? Without specifying varlist2,
the sort order within id will be scrambled.
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