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Re: st: loop within a loop


From   Matthew White <mwhite@poverty-action.org>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: loop within a loop
Date   Thu, 10 Nov 2011 16:24:06 -0500

Yes, though you'll want to reverse the list to get the order of the
variables the same as before:

foreach stat in mean max min {

Alternatively:

-start code-

local y v1_ v2_ v3_ v4_ ... v16_
loc stats min max mean

foreach x of local y {
	foreach stat of loc stats {
            egen `x'`stat' = row`stat'(`x'A - `x'C)
	    order `stat', before(`x'C)
	}
	order `x'C, before(`x'`:word 1 of `stats'')
}

- end code-

Best,
Matt

On Thu, Nov 10, 2011 at 4:06 PM, Steve Nakoneshny <scnakone@ucalgary.ca> wrote:
> Hi Matt,
>
> Thank you for the quick response! Despite -help foreach- and the two Stata Press books in front of me, I just wasn't getting it.
>
> After modifying my do file as per you suggestion, I realized I could also incorporate the -order- command into the nested loop thus:
>
> -start code-
>
> foreach x of local y    {
>        foreach stat in min max mean {
>                egen `x'`stat' = row`stat'(`x'A - `x'C)
>                order `x'`stat', after(`x'C)
>        }
> }
>
> -end code-
>
> Thanks again,
> Steve Nakoneshny
> scnakone@ucalgary.ca
>
>
>
>
> On 2011-11-10, at 1:49 PM, Matthew White wrote:
>
>> Hi Steve,
>>
>> -egen `x'`a' = row`a'(`x'A - `x'C)- is exactly along the lines you
>> want. You could try:
>>
>> -start code-
>>
>> local y v1_ v2_ v3_ v4_ ... v16_
>> local i 0
>>
>> foreach x of local y {
>>       foreach stat in min max mean {
>>           egen `x'`stat' = row`stat'(`x'A - `x'C)
>>       }
>>     order `x'min `x'max `x'mean, after(`x'C)
>> }
>>
>> - end code-
>>
>> Nothing beats reading the help file: -help foreach-.
>>
>> Best,
>> Matt
>>
>> On Thu, Nov 10, 2011 at 3:41 PM, Steve Nakoneshny <scnakone@ucalgary.ca> wrote:
>>> Dear Statalist,
>>>
>>> I'm working with a dataset of biomarker data. This dataset contains triplicate scores on 16 unique biomarker measures for a total of 48 variables. Each measure has a unique name (obviously) and each scoring of these appends a letter to the end of the varname like this: v1_A v1_B v1_C ... v16_A v16_B v16_C.
>>>
>>> Wanting to calculate new variables for min max and mean scores and then order these results relative to each biomarker measure, I thought I would write a loop to do so rather than write ~64 lines of code.
>>>
>>> This is what I did:
>>>
>>> -start code-
>>>
>>> local y v1_ v2_ v3_ v4_ ... v16_
>>> local i 0
>>>
>>> foreach x of local y    {
>>>        local ++i
>>>                egen `x'min = rowmin(`x'A - `x'C)
>>>                egen `x'max = rowmax(`x'A - `x'C)
>>>                egen `x'mean = rowmean(`x'A - `x'C)
>>>                order `x'min `x'max `x'mean, after(`x'C)
>>> }
>>>
>>> - end code-
>>>
>>> As far as I can tell, the code executes exactly as I wanted and I now have my new variables created and ordered as planned. What is bugging me though is thinking that I could combine the -egen- commands into a loop and nest it into the larger loop.
>>>
>>> I suspect that I would first have to create -local a min max mean- and rewrite the -egen- command as -egen `x'`a' = row`a'(`x'A - `x'C)- (and then delete the two superfluous -egen- commands). However, that in and of itself will not be sufficient and I don't know enough to provide the appropriate syntax to have the loop execute correctly. I am still relatively new to using loops and would appreciate some suggestions.
>>>
>>> Thanks,
>>> Steve Nakoneshny
>>> scnakone@ucalgary.ca
>>>
>>>
>>>
>>>
>>>
>>> *
>>> *   For searches and help try:
>>> *   http://www.stata.com/help.cgi?search
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>>> *   http://www.ats.ucla.edu/stat/stata/
>>>
>>
>>
>>
>> --
>> Matthew White
>> Data Coordinator
>> Innovations for Poverty Action
>> 101 Whitney Avenue, New Haven, CT 06510 USA
>> +1 434-305-9861
>> www.poverty-action.org
>>
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
>> *   http://www.stata.com/support/statalist/faq
>> *   http://www.ats.ucla.edu/stat/stata/
>
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>



-- 
Matthew White
Data Coordinator
Innovations for Poverty Action
101 Whitney Avenue, New Haven, CT 06510 USA
+1 434-305-9861
www.poverty-action.org

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


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