st: Question on loop over variable

[Guo Chen <chenx711@umn.edu>]

Hi, all:

I wanna calculate monthly average purchase price for all the products
in my data set, so I need loop over all values of variable "itemid".

I checked http://www.stata.com/support/faqs/data/foreach.html  and the
following code is the best I can do, but I still got error messege:


file C:\DOCUME~1\MPTMP026\LOCALS~1\Temp\ST_0000000t.tmp not found
r(601);

Can you please take a look at my code?

==========begin code=========
use data, replace

tempfile data

levelsof itemid, local(levels)

foreach l of local levels{
use "`data'", clear
keep if itemid == "`l'"
bys monthly: replace total_purchase_price = sum(extendedcost)
bys monthly: replace total_quantity = sum(itemqty)
replace average_purchase_price = total_purchase_price / total_quantity

bys monthly: gen i = [_n]== 1
drop if i != 1
outsheet using "C:\Documents and Settings\MPTMP026\Desktop\new\`l'.txt"
}



--
Guo Chen
University of Minnesota
Dept. of Applied Economics
125-E Ruttan Hall
1994 Buford Avenue
St. Paul, MN 55108
612-423-7031
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