Not knowing the highest value in advance would bite equally hard with
the method in your previous post, which works from 1 upwards to a
specified maximum, so that objection seems unconvincing to me.
Nick
[email protected]
Jeph Herrin
Thanks. I also thought of something like this, but
didn't want to pursue it, if that makes sense. For
one thing, I have literally thousands of variables and
don't know ahead of time what the highest number I
need is.
As for the structure, it may not be the worst, but it
is surely not the best.
Nick Cox wrote:
> Another way to do it:
>
> clonevar work = myvar
>
> qui forval i = 29(-1)1 {
> gen myvar_`i' = strpos(work, "`i'") > 0
> replace work = subinstr(work, "`i'", "", .)
> }
>
> Here 29 is in general whatever highest number you need.
>
> In words, in addition to the -strpos()- logic,
>
> 1. Work on a copy, because we're going to change it.
>
> 2. Work downwards, from high values down to 1.
>
> 3. Once you've checked for a longer string, zap it so that it doesn't
> later confuse the search for shorter strings.
>
> Incidentally, don't knock the format (or structure). When Uli Kohler
and
> I wrote up the tricks we knew for multiple responses (in this sense),
it
> was pretty clear to us that all such formats or structures have some
big
> advantages and disadvantages. Our efforts are accessible at
>
> FAQ . . . . . . . . . . . . . . . . . . . Dealing with multiple
> responses
> . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox and
U.
> Kohler
> 4/05 How do I deal with multiple responses?
> http://www.stata.com/support/faqs/data/multresp.html
>
> SJ-3-1 pr0008 Speaking Stata: On structure & shape: the case of
mult.
> resp.
> . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox &
U.
> Kohler
> Q1/03 SJ 3(1):81--99 (no
> commands)
> discussion of data manipulations for multiple response data
>
> Nick
> [email protected]
>
> Jeph Herrin
>
> Solved - this does it:
>
> forv i=1/9 {
> gen byte myvar_`i'= regexm(myvar,"^`i':|:`i':|:`i'$")
> }
>
>
> Jeph Herrin wrote:
>
>> I have a dataset in which many variables are in
>> the most useless format imaginable. If a question
>> has multiple checkboxes as possible answers, the
>> response is stored as a string, with a number indicating
>> each box checked and these numbers separated by colons.
>> Thus:
>>
>> myvar
>> 1:2:3:5:6:7:8:9
>> 1:2:3:6
>> 1:2:3:4:5:7:8:9
>> 1:2:3:5:7:9
>> 1:2:3:5:7:8:9
>> 2:3:4:6:9
>> 1:2:3:5:6:7:8:9
>> 1:2:7:8:9
>> 7:9
>>
>> This variable takes 9 values, so I want to split into 9
>> different indicator variables, myvar_1-myvar_9, each
>> indicating whether that number was selected. -split()-
>> does not work, because of the differing number of values
>> per string. That is, it produces myvar_1 which equals "7"
>> for the last obs.
>>
>> So I am looking for a way to check whether a given string
>> contains a given integer, which would allow me to
>>
>> forv i=1/9 {
>> gen byte myvar_`i'= [`i' is in myvar list]
>> }
>>
>> As long as there are just 9 values, I can use -strpos()-
>> to check for the presence of the digit, but some of my variables
>> run into tens and twenties, in which case eg searching for "1"
>> returns true even if there is only "11".
>>
>> The only solutions I see are to first -split()- and
>> then check all the new indicators, or run through a series of
>> checks such as (matches "1:" but not ":1"). I don't like
>> either: Is there a direct way to check to see if a given integer
>> is in the list?
>>
>> I think there may be a regex solution, but my Perl programming
>> days are so far behind me that I've not been able to come up
>> with one.
>
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