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st: Selecting part of a LARGE file
I have two files. File A has about 5000 unique values of the variable
PATENT, which is 7 characters long. File B has 16 million observations
and several million unique values for PATENT. I want to do some
manipulation involving File B, but only for the observations that
correspond to the patent values found in File A. I am currently using
merge on the two files to do this (actually mmerge as a wrapper for
ease), but wonder if there is an easier/faster way.
I attempted using vallist.ado in File A to generate a long local macro
(say, _useme) and then doing
use FileB if index(patent, "'useme'")
I get 0 observations in this case (even though I know there are some
matches). From the manual, it appears that index is limited to strings
of 80 characters, anyway.
Any better suggestions? Thank you in advance.
Assistant Professor of Strategy
College of Business Administration
University of Illinois at Urbana-Champaign
"Success is going from failure to failure without a loss of enthusiasm."
Sir Winston Churchill
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