This is the dreaded loop over observations. In
most problems it is unnecessary, including this
one. Thanks to the smart people at StataCorp,
you can go
gen newvar = strvar1 + substr("000",1, 3 - length(strvar2)) + strvar2
and the loop comes free as part of the innards of -generate-.
In Clare's problem, trim(strvar1), trim(strvar2) and
length(trim(strvar2)) might be needed and would do no
harm.
Nick
[email protected]
Richard Palmer-Jones
> * if your variables are strvar1 & strvar2
> gen str6 newvar = ""
> qui des
> local N = r(N)
> forval i = 1/`N' {
> local t1 = strvar1[`i']
>
> local t2 = strvar2[`i']
> local leng2 = length("`t2'")
> local dum2 = ""
> if `leng2' == 1 {
> local dum2 = "00"
> }
> else if `leng2' == 2 {
> local dum2 = "0"
> }
> local var = "`t1'`dum2'`t2'"
> replace newvar = "`var'" in `i'
> }
> list
>
> | strvar1 strvar2 newvar |
> |----------------------------|
> 1. | B 1 B001 |
> 2. | B 120 B120 |
> 3. | CCH 7 CCH007 |
> 4. | CCH 23 CCH023 |
> 5. | CCH 213 CCH213 |
> |----------------------------|
> 6. | UW 23 UW023 |
> 7. | UW 232 UW232 |
>
> Richard
>
> On 11/24/05, Ian Watson <[email protected]> wrote:
> > Clare
> >
> > I've reproduced your problem and compared it with
> yesterday's solution
> > and can only come up with one suggestion.
> >
> > When you infile the string and then split it, using the
> substr function,
> > the right hand component (which I called num in yesterday's
> post) has
> > leading blanks on it. These are then replaced by leading 0s
> using the
> > subinstr function.
> >
> > However, when you infile the string as two strings, Stata possibly
> > strips the leading blanks from it. Even though it has the
> designation of
> > a str3 type, it may not have the same "contents" as num did
> (which was
> > also a str3 type) because that latter was created from substr. That
> > is " 23" and "23" look the same on the screen, but they're
> not the same
> > data.
> >
> > This is only a guess, and I can't find an easy way to test
> it. But it
> > suggests you're better off reading your string in as a full
> string, then
> > splitting it, rather than as two strings. At least that
> works (even if
> > the reason is not altogether clear to me why).
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