st: Compact list of correlation, by cross-section

["Michael S. Hanson" <mshanson@wesleyan.edu>]

	I have two variables in a panel that I would like to compute the 
correlation by cross-sectional unit, then list in a compact way by 
cross section.  It's the listing that is the problem, as -by id: corr x 
y- yields many pages of output for my 50 cross-sections.  Ideally I'd 
like something similar to the output of -tabstat x y, by(id)- ... but 
-tabstat- only reports univariate statistics.

	I thought this was going to be relatively easy to code, but I ran into 
one large conceptual problem:


		decode id, gen(idstr)		// string for display
		egen idn = group(id)		// sequential numbers for loop
		forvalues i = 1/50 {
			quiet corr x y if idn == `i'
			disp idstr "  " `r(rho)' if idn == `i'
		}


Namely, -display- does not accept conditions (i.e., the -if-)!  
Neither, as far as I can tell, do any of the assignment commands (e.g. 
-generate-, -local-, etc.).  So I've pored over the manuals hoping to 
find an alternative approach, but I've come up completely empty.  I'm 
certain I am not thinking about the problem the "Stata way," but I 
cannot seem to figure out what that way would be.  I welcome any 
suggestions on how to accomplish what I am looking for.  TIA.

                                        -- Mike

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