On 9/25/03 12:09 PM, "Nicholas Winter" <[email protected]> wrote:
> At 07:14 PM 9/24/2003 -0400, you wrote:
>> Hi,
>>
>> Suppose I want to create 2 temporary datasets inside a -forval- loop, with
>> names indexed by the loop number (i.e., `results0', `results1'). Once I get
>> outside the loop, I want to append them using -dsconcat-, but since I
>> defined them inside the loop, they no longer exist.
>>
>> A more concrete example:
>>
>> forval k = 0(1)1 {
>>
>> tempname memhold
>> tempfile results
>>
>> postfile `memhold' var1 var2 var3 using `results'`k', replace
>>
>> forval y = 1998(1)2002 {
>> ...
>>
>> post `memhold' (`x') (`y') (`z')
>> }
>>
>> postclose `memhold'
>> }
>>
>> dsconcat `results0' `results1'
>>
>> Could someone offer a suggestion on how to do this, please? Much thanks.
>
> I think this isn't a scope problem, but a local macro naming issue. I
> think you need to modify the way you get and use the -tempfiles-.
>
> Currently in the loop you do:
>
> tempfile results
>
> then you post to a file called `results'`k' , which will be the name of the
> -tempfile- Stata gave you, with the number 0 or 1 appended. That might or
> might not even be a legal filename on your OS. Then outside your loop, you
> refer to the locals `results0' and `results1' -- you never defined those
> locals.
>
> Instead, your tempfile command should read:
>
> tempfile results`k'
>
> On the first iteration, this will create a local macro called `results0';
> on the second iteration it will create `results1'.
>
> So inside the loop, post to `results`k''
>
> Then at the end, after the loop, you can refer to `results0' and `results1'.
>
> By the way, I'm not clear why you need the -tempname- for the posting
> defined repeatedly; you could just define one outside the loop, and reuse
> it repeatedly.
>
>
> --Nick Winter
Yes, I think I didn't understand how -tempfile- works. I believe I have a
better grasp on this now.
This last point seems to be a good one. It's true, I don't need to define
-tempname- in each loop. I guess I had just put it with -tempfile- out of
habit. On the other hand, does it really make much difference? I don't
imagine my computing time is shortened noticeably by putting it outside the
loop, no?
-Danielle Ferry
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