Message-ID: <Pine.BSI.4.10.10005221449550.27263-100000@fellspt.charm.net>
Date: 2000-05-22T18:57:12Z
From: Scot W McNary
Subject: Selecting a random sample
Hi,
I'm trying to learn R and get an errand done at the same time. I have a
list of cases with ids numbered sequentially 1 to 403. I want to select
at random exactly 20 without replacement. Here's what I've tried so far:
> ids<-(1:403)
> pick<-runif(403)
> picklist<-as.data.frame(cbind(ids,pick))
> who<-subset(picklist, pick<20/403)
> who
This works, but I can have anywhere from 16 to 32 cases in the subset
'who', due to random variability in the runif generator. What's a more
efficient (and general) way to extract a subset of exactly n from a total
sample N?
Thanks in advance,
Scot
--
Scot W. McNary email:smcnary at charm.net
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