# st: Re: loop within loop

 From "Wang,Le" To Subject st: Re: loop within loop Date Mon, 18 Oct 2004 02:47:15 -0500

```Actually I also tried the following,

forvalues i = 1988(1)2003 {
forvalues j = 1(1)12  {
matrix accum R`i'`j' = a b c d e if year == `i' & month == `j',
nocons dev
matrix R`i'`j' = corr(R`i'`j')
replace corrab = R`i'`j'[1,1] if year == `i' & month == `j' &
corrab == .
}
}

Can anyone can tell me where i am wrong? Thanks.

Best,
Le
----- Original Message -----
From: "Wang,Le" <lew@mail.smu.edu>
To: <statalist@hsphsun2.harvard.edu>
Sent: Monday, October 18, 2004 2:40 AM
Subject: st: loop within loop

> Hi dear statalister,
>
> I have a question on loop within loop. I have the following data set
>
> year       month     date            a         b          c
> 88             1            1            .2         .5        .3
> .                1            2            .3         .6        .4
> .                1            3            .4         .7        .5
> .                2            1            .1         .2        .7
> .                2            2            .4         .5        .9
> .                2            3            .6          .7        1
> 89             1            1            .2         .5        .3
> .                1            2            .3         .6        .4
> .                1            3            .4         .7        .5
> .                2            1            .1         .2        .7
> .                2            2            .4         .5        .9
> .                2            3            .6          .7        1
>
> I could program the correlation by year as follows,
>
> g corrab = .
>
> forvalues i = 1988(1)2003{
>       matrix accum R`i' = a b c  if year == `i', nocons dev
>       matrix R`i' = corr(R`i')
>       replace corrab = R`i'[2,1] if year == `i' & corrab == .
> }
>
> However,  now I want to calculate the correlation between a and b by year
> and month. What should I do?? I tried the following, but it doesnot work.
>
> forvalues i = 1988(1)2003 {
>          local j = 1
>          while `j' < 13{
>           matrix accum R`i'`j' = a b c d e if year == `i' & month == `j',
> nocons dev
>           matrix R`i'`j' = corr(R`i'`j')
>           replace corrab = R`i'`j'[1,1] if year == `i' & month == `j' &
> corrab == .
>           local `j' = `j' + 1
>           }
> }
>
> Thanks a lot for your kind help.
>
> Best,
>
> Le
>
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```