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Re: st: Re: select three non-identical random elements
From
Tomáš Houška <[email protected]>
To
[email protected]
Subject
Re: st: Re: select three non-identical random elements
Date
Thu, 4 Apr 2013 14:38:28 +0200
Hi Joseph,
thank you for your tip! I was able to use that to solve my problem.
Tomas
2013/4/4 Joseph Coveney <[email protected]>:
> Tomáš Houška wrote:
>
> 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.
>
> --------------------------------------------------------------------------------
>
> Macro extended functions for manipulating lists (-help macrolists-) will help
> you to randomly sample without replacement from a local macro containing a list
> of words.
>
> As Nick mentions, there might be better ways in the long run using Mata, but
> this should get you going until then.
>
> Joseph Coveney
>
> .
> . local word_list one two three four five six
>
> .
> . local want 3
>
> .
> . set seed `=date("2013-04-03", "YMD")'
>
> .
> . local words : word count `word_list'
>
> . assert `want' <= `words'
>
> .
> . local loop 1
>
> . while `loop' <= `want' {
> 2. local randu = 1 + floor((`words' - 1) * runiform())
> 3. local random`loop' : word `randu' of `word_list'
> 4. local word_list : list word_list - random`loop'
> 5. local --words
> 6. local ++loop
> 7. }
>
> .
> . display "`random1'"
> five
>
> . display "`random2'"
> one
>
> . display "`random3'"
> four
>
>
> *
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