[R] Conditional randomization of groups

[Meyners, Michael, LAUSANNE, AppliedMathematics]

Hi "unknown",

As a quick patch, try something like

mydata$Set <- 1
mydata$Set[c(sample(mydata$ID[mydata$Type=="A"],
ifelse(runif(1)<1/2,2,3)), sample(mydata$ID[mydata$Type=="B"], 3) )[1:5]
] <- 2
 
HTH, Michael

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of yabado
Sent: Donnerstag, 6. August 2009 23:29
To: r-help at r-project.org
Subject: [R] Conditional randomization of groups


Hi

I have a data set which is like this:

Data

ID   Type
1       A
2       B 
3       A
4       A
5       A
6       B
7       B
8       A
9       B
10     B

As you can see, there are 5 A and 5 B. Now, I want to a randomization of
the data set which will assign 5 ID  to a new group called "Set1" and
and the other 5 to "Set2"

The Set1 and Set2 will be either: 
Set1 (A A A B B ) and Set2 (A A B B B)
or
Set1(A A B B B) and Set2 (A A A B B).

Each new group need to have at two A and two B, and one more B or A.
Except this condition, everything else (ID, permutation, selection to
Set1 and
Set2) need to be random.

Can anyone show me how to do the randomization?


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