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Re: st: select three non-identical random elements


From   Nick Cox <njcoxstata@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: select three non-identical random elements
Date   Thu, 4 Apr 2013 11:09:33 +0100

-levelsof- is a command, not a macro. See e.g.

http://www.stata.com/statalist/archive/2008-08/msg01258.html

Here's an example of one way to do it.

sysuse auto
egen tag = tag(rep78)
sort tag
levelsof rep78 in -3/L

You might well want to introduce more randomness that you could control.

If this problem arose again and again for me, and no one suggested a
better solution, I'd write a Mata-based command.
Nick
njcoxstata@gmail.com


On 4 April 2013 10:42, Tomáš Houška <xbender@gmail.com> wrote:
> Dear Statalist,
>
> I have list of items create by -levelsof- macro and I would like to select
> three items from that list at random and for them to be non-repetitive
> (i.e. each one can appear only once in the selection).
>
> Lets say I have a list -local list "one two three four five six"- and I
> would like to get
> local random1 =
> local random2 =
> local random3 =
>
> where each one is a random selection from the local list and each item
> appears at max once.
> I would appreciate any help on how to do that.
>
> Thank you!
> Tomas
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