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Re: Re: st: I can't get fs to work from inside a do file


From   n j cox <n.j.cox@durham.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: Re: st: I can't get fs to work from inside a do file
Date   Mon, 18 Feb 2008 14:31:23 +0000

To expand on points already made concisely by Michael Blasnik and with examples by Joseph Coveney:

What is perhaps being overlooked here is that -display- is smart enough to evaluate an expression. After all, if you type

. di 2 + 2

you expect (1) evaluation: 2 + 2 to be evaluated as 4; (2) display: printing of 4. Only if you type

. di "2 + 2"

does the argument get displayed as shown.

Similarly, when -display- sees r(files), i.e.

di r(files)

it evaluates first -- Stata works out what is inside r(files) -- and then displays. This is all consistent with

r(files)

being counted as a single word, namely "r(files)".

Thus compare these four; some of the differences are stark and some a little more subtle.

. di "r(files)"
. di r(files)
. di `r(files)'
. di "`r(files)'"

Similarly compare these two:

. local nw : word count r(files)

. local nw : word count `r(files)'

In the first, the -word count- is just looking at "r(files)" which although it means something to you -- and indeed to -display- -- is just a text string as far as -word count- is concerned.

In the second `r(files)' is treated like a local macro, so that macro substitution takes place before -word count- ever gets to work. As the individual filenames are bound in " " those to Stata are the words.

(Recall Stata's rules on words: spaces separate words, except that (compound) double quotes override that and bind together again.)

Nick
n.j.cox@durham.ac.uk

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From: "Gabi Huiber" <ghuiber@gmail.com>
Subject: Re: st: I can't get fs to work from inside a do file
Date: Sun, 17 Feb 2008 20:45:19 -0500

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Michael,

Thank you for replying to my post. Below is an actual copy of my Stata
results window, after the do-file with the fs command rolled to the
end without executing. Remember that we started here:

. ***************** CALL DO-FILES SPECIFIC TO EACH ${paper} HERE
.
. fs prototype/${paper}/*.do
> local dofiles=r(files)
>
> foreach k of local dofiles {
> do "prototype/${paper}/`k'"
> }
>
> clear
> di "goodbye"

end of do-file

So I went to the command window and copied the fs line into it, as shown below:

. fs prototype/${paper}/*.do
dna_step1_target.do dna_step3_report1.do dna_step5_report2.do
dna_step2_snapshot1.do dna_step4_snapshot2.do

Clearly, it worked. Next, I declared the local eenie:

. local eenie r(files)

Then I checked to see that it showed what I thought it would:

. di `eenie'
"dna_step1_target.do" "dna_step2_snapshot1.do" "dna_step3_report1.do"
"dna_step4_snapshot2.do" "dna_step5_rep
> ort2.do"

And it did, but look:

. local x: word count `eenie'

. di `x'
1

Even though `eenie' seems to have five distinct words delimited by
quotes, it only has one. The quotes are somehow embedded in it. So I
tried evaluating the r(files) expression, like in `meenie' below:

. local meenie=r(files)

. di `meenie'
dna_step1_target.dodna_step2_snapshot1.dodna_step3_report1.dodna_step4_snapshot2.dodna_step5_report2.do

Now the thing clearly looks like it's one uninterrupted word, but it's
not. Look:

. local y: word count `meenie'

. di `y'
5

So with the risk that it would truncate the content of the ${paper}
folder to 244 characters, using the = sign looked like a good idea at
the time. Now I will move on to trying out Joseph Coveney's syntax and
see how that works. The 244 character limitation is not binding now,
but it might be in the future. I want to avoid it if I can. This reply
was just for the entertainment of the interested parties. I think it's
at least curious how Stata looks like it does one thing, and does
another.

Thanks again to all,

Gabi


On Feb 16, 2008 4:48 PM, Michael Blasnik <michael.blasnik@verizon.net> wrote:
> ...
>
> I hope you realize that your line
>
> local dofiles r(files)
>
> simply places the text string "r(files)" into the local macro dofiles. That is
> why word count comes up with one word. You need to expand the local macro when
> assigning it to dofiles, like this:
>
> local dofiles `r(files)'
>
> If you use the equals sign, then the list will be truncated at 244 characters.
> Without the equals sign it is nearly limitless.
>
> Michael Blasnik
>
>
> ----- Original Message -----
> "Gabi Huiber" wrote:
> >If you do
> >
> > local dofiles r(files)
> >
> > you get a string of all their names in a single word. I checked with
> > word count `dofiles'. That, of course, defeats the foreach loop. It's
> > bizarre, because this single-word string shows the do-file names
> > neatly delimited with spaces, whereas if you do
> >
> > local dofiles=r(files)
> >
> > like I did, the do-file names in that folder look like they're all
> > strung together as in file1.dofile2.do[...] yet the local `dofiles'
> > does have five distinct words, one for each do-file, as it should. Try
> > it with one of your do-file directories to see what I mean. Of course
> > running the foreach loop directly off the `r(files)' local fixes the
> > problem, but it's still a strange one, don't you think?
>
>
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