st: Re: macros

[baum <baum@bc.edu>]

--On Friday, July 26, 2002 2:33 -0400 Chris wrote:

> i'm trying to figure out the macro basics & can't seem to find any simple
> examples on the web or in the manual.  if someone could please post the
> text of a simple *.do file that uses macros, i'd really really appreciate
> it.  i'm using stata 7.
>
> i'd also really appreciate any suggestions on my specific problem that i'm
> trying to solve w/ macros:
>
> to take variables (air_reg1, air_reg2, ..., air_reg24)
> and (voc_reg1, ..., voc_reg24)
>
> and to produce the sum of the products:
>
> air_reg1*voc_reg1 + air_reg2*voc_reg2 + ... + air_reg24*voc_reg24
>
> for a bunch of different sets of variables ({air,voc} is one example) w/ a
> large dataset.
Look at any ADO file that does the kind of thing you're interested in. 
There are also a number of FAQs that use macros in illustrating various 
points.

For the sort of thing you're talking about, Nick Cox' Speaking Stata 
columns in Stata Journal would be a very useful reference. Generally 
speaking, the Programming manual is a very good thing to have; if you only 
have the Users' Guide and Ref Man available, you should see about getting a 
copy of [P] (available a la carte from the Stata Bookstore, or the Stata 
GradPlan if U.Chicago participates).

For what you describe try

gen result = 0
forvalues i=1/24 {
	replace result = result + air_reg`i' * voc_reg`i'
	}

If the air and voc variables are doubles, make result a double as well.

Kit

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