Re: st: substringing long, varying length text variables into individual variables

[Todd Wagner <twagner@stanford.edu>]

Thanks, Tom.

Todd

At 02:47 PM 4/2/2008, you wrote:
> Hi Todd,
>
> I use Stata 8 and I cannot touch strings with more that 80 chars. If
> I'm not mistaken this is not the case for newer releases... so i use a
> dummy example with less than 80 chars below...  I presume this would
> work in Stata 9/10 - if not don't shoot me.
>
> e.g., use
>
> 1   Str A|Str B|Str C|Str D
> 2   Str A|Str B|Str D
> 3   Str D
>
> A. change the spaces to underscores in a clone variable, and then the
> "|" to spaces. The -wordcount- and -word- functions of Stata use
> spaces to parse (if someone knows how to use a different separator in
> these functions, this step is superfluous.)
>
> . gen newString = subinstr(originalString," ", "_",.)
> . replace newString = subinstr(newString,"|", " ",.)
>
> B. get the maximum number of "words" per record
> . gen howMany = wordcount(newString)
> . summ howMany
> .forval i=1/`howMany' {
> .       gen des_`i' = word(newString,`i')
> .}
>
>
> This gives you
>
> des_1   des_2   des_3   des_4
>
> Str_A   Str_B   Str_C   Str_D
> Str_A   Str_B   Str_D
> Str_D
>
> C.  You can easily restore the spaces in the strings in des_1 to des_4
> by changing the underscores back to spaces.
>
> D. However, are you sure you want this as a final step? If you want to
> have e.g. 4 dummies (one for Str_A, one for Str_B etc.):
>
> str_a str_b str_c str_d
> 1       1        1      1
> 1       1        0      1
> 0       0        0      1
>
> you would have to continue with reshaping long per record and then
> back again reshaping wide per content of the string variable... Some
> -encode-ing  will probably necessary also in the meanwhile...
>
>
> That being said I'd do the "silly way" (using python or vim or sed) to
> manipulate the strings outside Stata...
>
>
> hth
>
> tom
>
>
>
>
>
> On undefined, Todd Wagner <twagner@stanford.edu> wrote:
> > Hi,
> >
> >  I have data from a publicly available database
> >  (clinicaltrials.gov).  This database has a number of text variables
> >  that I want to break into individual variables and I could use some help.
> >
> >  For example, one of the variables is called study designs.  Here are
> >  some data from the study designs variable
> >
> >  Treatment|Randomized|Double-Blind|Placebo Control|Parallel
> >  Assignment|Safety/Efficacy Study
> >  Prevention|Randomized|Open Label|Active Control|Parallel
> >  Assignment|Bio-equivalence Study
> >  Prevention|Randomized|Double Blind (Subject, Caregiver, Investigator,
> >  Outcomes Assessor)|Crossover Assignment
> >  Randomized|Single Blind|Active Control|Parallel Assignment
> >  Natural History|Cross-Sectional|Case Control|Prospective Study
> >  Treatment|Randomized|Open Label|Active Control|Parallel
> >  Assignment|Efficacy Study
> >  Treatment|Randomized|Double-Blind|Placebo Control|Single Group
> >  Assignment|Safety/Efficacy Study
> >  Treatment|Randomized|Open Label|Placebo Control|Parallel
> >  Assignment|Safety/Efficacy Study
> >  Treatment|Randomized|Double-Blind|Active Control|Parallel
> >  Assignment|Safety/Efficacy Study
> >  Prevention|Randomized|Double-Blind|Placebo Control|Parallel
> >  Assignment|Safety/Efficacy Study
> >  Treatment|Randomized|Single Blind (Investigator)|Placebo
> >  Control|Parallel Assignment
> >  Treatment|Randomized|Open Label|Active Control|Parallel
> >  Assignment|Efficacy Study
> >
> >  What I want to do is parse this text using the "|" into 
> individual variables
> >
> >  So the first case would be
> >  des1            des2            des3            des4 
>         des5                    des6
> >  Treatment       Randomized      Double-Blind    Placebo 
> Control         Parallel
> >  Assignment      Safety/Efficacy Study
> >
> >  I can think of a brute force way where I save this variable and my id
> >  variable, change | to a comma, output as text, read the text into
> >  stata as a comma separated file, and then merge it back into my
> >  data.  Sounds silly, but perhaps it is the easiest.  Any other ideas?
> >
> >  Thanks,
> >
> >  Todd
> >
> >  *
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> >
> *
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*
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