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RE: st: RE: collapse is too memory demanding


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: RE: collapse is too memory demanding
Date   Tue, 27 Jul 2010 18:13:06 +0100

Even if that weren't true, two variables rather than one are no problem
for -tabstat- because 

. egen both = group(first second), label 

could be used to give a composite variable. 

Nick 
n.j.cox@durham.ac.uk 

Martin Weiss

" The -tabstat- is not exactly what I need, because it allows just one
varname in the 
by(varname) option and I need two."

But note -h tabstat-:  "Do not confuse the by() option with the by
prefix;
both may be specified." 

*************
sysuse auto, clear
by foreign rep78, sort: tabstat price, statistics(mean)
columns(variables)
tabstat price, statistics(mean) by(rep78) columns(variables)
*************

Oliver Jones

Thanks for your advice.

Today I spoke to a colleague on the phone and he thinks that -collapse-
saves the results (in 
my case the sums) in a new double variable in the original dataset.

The answer to my question therefore might be, that in my case I
approximately need additional 
  70*8*20000000 bytes, i.e. 10.6 GB free memory.
The calculation goes as follows: I collapse a varlist of 70 variables,
thus
stata generates 70 
double variables each requiring 8 bytes per observation and I got 20
million
observations...

@ Nick: The -tabstat- is not exactly what I need, because it allows just
one
varname in the 
by(varname) option and I need two. Besides I want to save the results in
a
file.

@ David: The workaround is going to be the solution!


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