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Re: st: Generating blank observations


From   "Le Wang" <statauser@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Generating blank observations
Date   Wed, 8 Nov 2006 11:13:52 -0600

Patrick,

I think you can try the following codes. It worked when I was trying
to solve your artificial problem, but I am not quite sure if it will
work in other cases.

sort x
local n=_N+1        /* Notice that `n' here is _N+1 instead of _N	*/
local N=x[_N]+1

set obs `N'
g flag=(x==.)
replace x = x[1]+1 if _n==`n'
replace x = x[_n-1]+2 if x == .

Le

On 11/8/06, Patrick Woodburn <patrick.woodburn@mrcuganda.org> wrote:
Dear Statalist,

This is my first post to the list, and I hope it is clear enough.  I
just have one question for now:

If I have an id variable called "var1" with a selection of unique values
in a given range of integers (eg the values 1, 3, 5, 6, 7, and 9), and I
want to create new observations which contain each missing value in that
range and are blank for all other variables (eg new observations
containing 2, 4, 8 and 10) and a new variable to flag that they have
been artificially generated, what do I do?  Currently, all I can think
of is the rather roundabout way of doing it below, but I can't help but
think that surely there must be a more efficient method.

Best regards,

Patrick


*Code begins (dataset already open)

preserve
keep var1
drop if var1==.
bysort var1: assert _n==1
gen flag=0
gen id=1
reshape wide flag, i(id) j(var1)
forvalues i=1/10 {
   cap gen flag`i'=1
}
reshape long flag, i(id) j(var1)
drop id
keep if flag==1
save var1skippedvalues
restore
append using var1skippedvalues

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--
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Le Wang, Ph.D.
Minnesota Population Center
University of Minnesota
(o) 612-624-5818
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