Thursday, March 16, 2006

RE: st: looping over parallel lists - is there a alternative to "for"?

As has been said, -for- divides the world (like Marmite, if you know what that is).

The two camps are, naturally, "for" and "against".

Once you have seen the light on -forvalues- and -foreach-, you never want to go back.

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

Ada Ma > I suppose you can have three globals and then have one loop to loop > through them? Some samples can be found in C Baum's "A little bit of > Stata programming goes a long way ..." > > http://www.stata.com/meeting/11uk/baum.pdf > > I quite like the -for- command as well, sometimes I only want to loop > one line of command and using commands like -forvalue- and -foreach- > gets a bit complicated. And speaking for myself, using -for- would > save me from making typos like using ) instead of }. > > > > On 3/16/06, Gawrich Stefan <s.gawrich@hlpug.hessen.de> wrote: > > Hi, > > > > I do a lot of routine or repetitive data analysis and use > loops and lists > > frequently (btw, thx to Nick Cox, his "How to fact lists > with fortitude" > > helped me a lot). > > > > I'm wondering why the "for"-command is officialy out of > date in Stata while > > one of it's best features - the use of parallel lists - > can't be done > > otherwise. Or am I missing something? > > > > One example: I routinely map ten different diseases with > tmap and save the > > maps as a graphic file. > > > > for var var1-var10 \ any "Disease1" "Disease2" [...] \ any > "Filename1" > > "Filename2" [...] : /// > > tmap choro X, id(county) map("county-Coordinates.dta") > title("Y") \ graph > > export "Z.png", replace > > > > In this example each graph is determined by something like > a 3-tuple of > > variable, title and saving-filename. > > This is just basic code, in real life the code blows up and > becomes hard to > > read, as we all know, "for" has some disadvantages. > > So if it can be done in a more structured manner, I would > like to know...

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