Bookmark and Share

Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

st: nested loops with varying degrees of nesting


From   David Kantor <kantor.d@att.net>
To   Statalist <statalist@hsphsun2.harvard.edu>
Subject   st: nested loops with varying degrees of nesting
Date   Tue, 01 Oct 2013 18:04:49 -0400

Hello all,
I would like to write a program that involves nested loops, where the degree of nesting is flexible. Consider the following simplified shell of a program. c1, c2, c3 are options that, for each one that is present, an additional a level of looping should be invoked.

prog def t1
syntax , [c1 c2 c3]

if "`c1'" ~= "" {
	local loop1 "forvalues d1 = 1/4 {"
	local loop1end "}"
}

if "`c2'" ~= "" {
	local loop2 "forvalues d2 = 1/4 {"
	local loop2end "}"
}

if "`c3'" ~= "" {
	local loop3 "forvalues d3 = 1/4 {"
	local loop3end "}"
}

`loop1'
`loop2'
`loop3'
disp "`d1' `d2' `d3'"
`loop3end'
`loop2end'
`loop1end'

end

----

When this runs, with one or more of the c1,c2,c3 options, I get
unrecognized command:  } invalid command name
--just the same as when I type
}
in the command window.
Evidently, a macro can stand for a command, but not "}" -- or "}" is not a command..

Does anyone have an Idea of how to accomplish this goal? I do have one idea, involving counting the number of loops:
if num_loops==1 {
	forvalues d1 = 1/4 {
	do_stuff
	}
}
else if num_loops==2 {
	forvalues d1 = 1/4 {
		forvalues d2 = 1/4 {
		do_stuff
		}
	}
else if num_loops==3 {
	forvalues d1 = 1/4 {
		forvalues d2 = 1/4 {
			forvalues d3 = 1/4 {
			do_stuff
			}
		}
	}
}

-- but I'd rather do something more succinct, if possible; my actual program may have up to 8 levels of nesting.
Does anyone have a suggestion?
(I do have another idea: build the entire nested looping command into one macro; I have not tried this yet.)
I use Stata 10.
Thanks
--David

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


© Copyright 1996–2018 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   Site index