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From |
Pablo Mitnik <pmitnik@ssc.wisc.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: Using Mata within a foreach loop = r(1) |

Date |
Fri, 07 Dec 2007 11:10:05 -0600 |

Thanks much for your answer -- this greatly clarifies things.

This way foreach treats end statements seems rather undesirable, doesn't it? And, yes, at least it should be in the help somewhere.

Pablo

Austin Nichols wrote:

Pablo Mitnik <pmitnik@ssc.wisc.edu>:--

You are not back in Stata; you never entered Mata. The -foreach- loop

aggregates all the commands before running, one of which is -end-,

which exits the loop and executes none of it.

Try

foreach i in 1 2 {

di `i'

end

}

to see what I mean. A similar problem arises is you try to -input-

data inside a -program- etc. The use of -end- to end many commands is

somewhat problematic in this case. I agree that -help end- should

explain this.

On 12/7/07, Pablo Mitnik <pmitnik@ssc.wisc.edu> wrote:

Nick Cox wrote:*

The answer to your 2 is Yes, with some exceptions for good reasons, asWhy am I back in Stata at this point?

when you

call Stata from Mata, but that is not the issue as I understand it.

The issue is that at that point in your code you are back in Stata and

so

(in context) -end- is illegal.

There can be no legal or meaningful -end- of a state without some--

beginning

that defines the start of that state (cf. much philosophy and all

eschatology).

Less enigmatically, in Stata -end- on a line by itself can indicate the

end of

a program which started with a -program- statement, and in Mata -end-

indicates

a desire to return to Stata. -help end- returns nothing, because -end-

is

not a statement by itself. But -search end- brings up some pointers,

some

of which are relevant to your 1.

It's a hard lesson that Stata's not behaving as you would guess, imagine

or prefer

does not in itself constitute a bug.

Pablo Mitnik

Thanks much for the suggestion . I can do that, and will probably do it.

But:

1. Is there a documented "end" command in Stata? Typing "help end"

returns nothing, while "search end" only returns the Mata end statement.

2. If I am "within Mata," shouldn't everything be run in Mata?

Maarten buis wrote:

--- Pablo Mitnik <pmitnik@ssc.wisc.edu> wrote:

This is rather inconvenient when you have a longer code to run in

Mata; and I haven't found any explanation in the manuals why the code

*with "mata" and "end" shouldn't work -- my bet is that this is a bug.The end command is run in Stata not Mata, so you get the correct error

message.

The way to do this in a more convenient way is to first create a mata

function, so within the loop all you need is a single call to Mata.

This is explained in terms of .ado programming in -help m1_ado-.

* For searches and help try:

* http://www.stata.com/support/faqs/res/findit.html

* http://www.stata.com/support/statalist/faq

* http://www.ats.ucla.edu/stat/stata/

Pablo A. Mitnik

University of Wisconsin-Madison (http://www.wisc.edu/ )

Department of Sociology ( http://www.ssc.wisc.edu/soc/)

Center on Wisconsin Strategy (http://www.cows.org/ )

1180 Observatory Drive

Room 7114A

Madison, WI 53706

TEL (608) 2621839

E-mail: pmitnik@ssc.wisc.edu

*

* For searches and help try:

* http://www.stata.com/support/faqs/res/findit.html

* http://www.stata.com/support/statalist/faq

* http://www.ats.ucla.edu/stat/stata/

* For searches and help try:

* http://www.stata.com/support/faqs/res/findit.html

* http://www.stata.com/support/statalist/faq

* http://www.ats.ucla.edu/stat/stata/

Pablo A. Mitnik

University of Wisconsin-Madison (http://www.wisc.edu/ )

Department of Sociology ( http://www.ssc.wisc.edu/soc/)

Center on Wisconsin Strategy (http://www.cows.org/ )

1180 Observatory Drive

Room 7114A

Madison, WI 53706

TEL (608) 2621839

E-mail: pmitnik@ssc.wisc.edu

*

* For searches and help try:

* http://www.stata.com/support/faqs/res/findit.html

* http://www.stata.com/support/statalist/faq

* http://www.ats.ucla.edu/stat/stata/

**References**:**Re: st: RE: Using Mata within a foreach loop = r(1)***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**Re: st: RE: Using Mata within a foreach loop = r(1)***From:*Pablo Mitnik <pmitnik@ssc.wisc.edu>

**RE: st: RE: Using Mata within a foreach loop = r(1)***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: Using Mata within a foreach loop = r(1)***From:*Pablo Mitnik <pmitnik@ssc.wisc.edu>

**Re: st: RE: Using Mata within a foreach loop = r(1)***From:*"Austin Nichols" <austinnichols@gmail.com>

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