Thanks Nick,
I tried the -statsby- command as Scott Merryman suggested and the -forval-
command that you are suggesting. But both these take almost exactly the same
amount of time as the -while- looping command... (Given my program code,
each simulation round is taking about 240-330 seconds, and I have got 1000
simulation rounds, if not more).
The -by- command is so much faster than the -while- command...
If I compare
by month: regress returns factor
vs.
local i = 1
while i <= 1000 {
regress returns factor if `i' == month
local i = `i' + 1
}
I find that the -by- command is atleast 15-20 times faster than the -while-
loop.
Given this, it would be really wonderful to be able to execute multiple
commands under -by-...
Some wishful thinking!
----- Original Message -----
From: "Nick Cox" <[email protected]>
To: <[email protected]>
Sent: Saturday, June 26, 2004 8:18 AM
Subject: st: RE: Multiple commands under "By varlist"?
> The short answer is that -by:- cannot
> be extended in this way. But there
> are several nearly equivalent procedures.
>
> Scott Merryman suggested -statsby-
> which is one good answer. You may
> or may not want the data reduction
> (collapsing of the data) that produces.
>
> You could write a program to be "byable".
> That way, an arbitrarily complex operation
> can be carried out by your own program.
>
> For this kind of example, however, an approach
> based on -forval- or -foreach- is indicated.
> You may want something like
>
> gen tintcp = .
> gen tslope = .
> forval i = 1/12 {
> regress returns factor if month == `i'
> replace tintcp = _b[_con] if month == `i'
> replace tslope = _b[factor] if month == `i'
> }
>
> There is a much fuller discussion at
> http://www.stata.com/support/faqs/data/foreach.html
>
> Nick
> [email protected]
>
> Subhankar Nayak
> >
> > Is it possible to give multiple commands following a particular
> > by varlist command?
> >
> > Can I give something like:
> >
> > by month: {
> > regress returns factor
> > replace tintcp = _b[_con]
> > replace tslope = _b[factor]
> > }
> >
> >
> > Of course, what I give here is not working, but is there
> > anyway to make it functional?
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
