st: re: averaging over a whole bunch of variables

[Kit Baum <baum@bc.edu>]

Then Kelly said

now suppose I had to do this operation in 100 different variabes (call 
them
var1-var100), how can i code a simple loot to do that?

i want to perform this within each variable: gen  
Var2=(Var1+Var1[_n-1])/2
if mod(_n,2)==0

(even _n calculations are fine...)

Thanks!


Generalization of the last solution. Hardly likely to be the most 
elegant way to skin this particular feline, but---

clear
set obs 100
forv i=1/100 {
	g var`i' = _n+`i'-1
	}	

// define the avg function and save as .mo (compiled object)

mata:
	void avg(string vname)
	{
	vnew = vname + "A"
	v1=st_data(.,vname,0)
	v3 = colshape(v1',2) * J(2,1,0.5)
	res=st_addvar("float",vnew)
	st_store((1,rows(v3)),res,v3)
	}
	mata mosave avg(), replace
	end
	
// now apply the avg function to each of the 100 variables; name the 
averaged version of each with
// suffix A

forv i=1/100 {
	mata avg("var`i'")
	}



Kit Baum, Boston College Economics
http://ideas.repec.org/e/pba1.html

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