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Re: st: Double loop over unbalanced panel


From   Fernando Luco <flucoestatalist@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Double loop over unbalanced panel
Date   Fri, 2 Nov 2012 16:00:10 -0500

Hi Nick,

The data and the formula look as follows

input id t str1 ch p str1 chh ph cont con_c chc
1 1 "a" 2 "" . 1 0.5 1 1
1 2 "b" 3 "a" 4 3 1 .
1 2 "b" 3 "a" 4 3 1 .
1 3 "a" 1 "b" 2 2 2 .
1 4 "c" 4 "a" 3 3 .75 .
1 5 "d" 2 "c" 5 1 .5 .
2 3 "d" 2 "" . 1 1 2
2 4 "a" 3 "d" 3 3 1 .
2 5 "b" 1 "a" 2 2 2 .
2 6 "a" 2 "b" 2 1 .5 .
end

foreach k of numlist 1/2{
foreach w of numlist 2/T_k{
replace chc=(chc[`w'-1]*ph+cont)/p if _n==`w' & id==`k'
}
}

Thanks,

Fernando

On Fri, Nov 2, 2012 at 3:39 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> I think the best advice depends on what -formula()- is, which you
> don't tell us.
>
> That said
>
> foreach of numlist ...
>
> in both your examples can be recast more simply as -forval- loops.
>
> Nick
>
> On Fri, Nov 2, 2012 at 8:12 PM, Fernando Luco <flucoestatalist@gmail.com> wrote:
>> Hi,
>>
>> I have an unbalanced panel and I need to do a loop over individuals and
>> observations. My data looks as follows (I have other variables that are not
>> represented in this example)
>>
>> id t  chc
>> 1 1 .5
>> 1 2 .
>> 1 3 .
>> 1 4 .
>> 1 5 .
>> 2 3 1
>> 2 4 .
>> 2 5 .
>> 2 6 .
>>
>> What I want to do is, for each individual (id) to complete the values in
>> chc according to a formula that depends on other variables. However, the
>> number of times that each individual appears differs across individuals. I
>> would like to do something such as
>>
>> foreach k of numlist 1/2 { /*the 2 has to be changed to the total number of
>> individuals*/
>> foreach w of numlist 2/T_k { /* where T_k corresponds to the number of
>> times individual 2 appears*/
>> replace chc=formula(`w')
>> }
>> }
>>
>> I don't know how to define T_k in the correct way such that it varies
>> across individuals (so 5 for individual 1 and 4 for individual 2).
>>
>> Thanks,
>>
>> Fernando
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