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Re: st: Need help with transforming dataset, please


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Need help with transforming dataset, please
Date   Tue, 26 Feb 2013 07:52:05 +0000

Note that this case is documented, at least in terms of an aphorism or
slogan, within

http://www.stata.com/support/faqs/data-management/problems-with-reshape/

The slogan is "You may need two reshapes to get to where you want to be".

Nick

On Tue, Feb 26, 2013 at 12:32 AM, Nick Cox <njcoxstata@gmail.com> wrote:
> . reshape long Subject Grade, i(StudId)
> (note: j = 1 2 3 4)
>
> Data                               wide   ->   long
> -----------------------------------------------------------------------------
> Number of obs.                        4   ->      16
> Number of variables                  10   ->       5
> j variable (4 values)                     ->   _j
> xij variables:
>          Subject1 Subject2 ... Subject4   ->   Subject
>                Grade1 Grade2 ... Grade4   ->   Grade
> -----------------------------------------------------------------------------
>
> . drop if missing(Subject)
> (2 observations deleted)
>
> . replace Subject = proper(Subject)
> (14 real changes made)
>
> . drop _j
>
> . reshape wide Grade , string i(StudId) j(Subject)
> (note: j = English French Geog Math)
>
> Data                               long   ->   wide
> -----------------------------------------------------------------------------
> Number of obs.                       14   ->       4
> Number of variables                   4   ->       6
> j variable (4 values)           Subject   ->   (dropped)
> xij variables:
>                                   Grade   ->   GradeEnglish
> GradeFrench ... GradeMath
> -----------------------------------------------------------------------------
>
> . renpfix Grade
>
> . l
>
>      +--------------------------------------------------+
>      | StudId   English   French   Geog   Math   Gender |
>      |--------------------------------------------------|
>   1. |    121         4        5      5      3        F |
>   2. |    122         4        .      5      5        F |
>   3. |    123         3        2      3      1        M |
>   4. |    124         2        .      1      2        M |
>      +--------------------------------------------------+
>
> Here's the code in one
>
> reshape long Subject Grade, i(StudId)
> drop if missing(Subject)
> replace Subject = proper(Subject)
> drop _j
> reshape wide Grade , string i(StudId) j(Subject)
> renpfix Grade
> l
>
> Nick
>
> On Tue, Feb 26, 2013 at 12:18 AM, Bidemi Carrol <bidemi@gmail.com> wrote:
>
>> I would appreciate some help with transforming the dataset below.
>> Reshape does not seem to work, but I may be applying it wrong.
>>
>> The original dataset is as follows (with many more grade and subject
>> combinations):
>>
>> StudId Gender  Subject1 Grade1 Subject2  Grade2   Subject3  Grade3
>> Subject4  Grade4
>> 121    F           MATH       3        ENGLISH  4           GEOG     5
>>         FRENCH  5
>> 122    F           ENGLISH  4        GEOG      5           MATH      5
>> 123    M          FRENCH   2        ENGLISH  3           MATH      1
>>        GEOG      3
>> 124    M          GEOG       1        MATH       2          ENGLISH  2
>>
>> I would like it to look like this:
>>
>> StudID  Gender  Math  English  French  Geog
>> 121        F          3         4             5        5
>> 122        F          5         4                       5
>> 123        M         1         3             2         3
>> 124        M          2        2                        1
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