From: Dimitris Rizopoulos <dimitrios.rizopoulos_at_student.kuleuven.ac.be>

Date: Tue 21 Jun 2005 - 22:54:48 EST

Dimitris Rizopoulos

Ph.D. Student

Biostatistical Centre

School of Public Health

Catholic University of Leuven

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Tue Jun 21 22:58:52 2005

Date: Tue 21 Jun 2005 - 22:54:48 EST

try this:

X <- factor(sample(c("A", "B", "C"), 10, TRUE), levels = c("A", "B",
"C"))

Y <- factor(sample(c("A", "B", "C"), 10, TRUE), levels = c("A", "B",
"C"))

#############

table(X, Y)

I hope it helps.

Best,

Dimitris

Dimitris Rizopoulos

Ph.D. Student

Biostatistical Centre

School of Public Health

Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium

Tel: +32/16/336899 Fax: +32/16/337015 Web: http://www.med.kuleuven.be/biostat/ http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm

- Original Message ----- From: "zhihua li" <lzhtom@hotmail.com> To: <r-help@stat.math.ethz.ch> Sent: Tuesday, June 21, 2005 2:46 PM Subject: [R] how to count "associated" factors?

> hi netters

*>
**> Suppose I have a factor X, with 10 elements and 3 levels: A B B C A
**> C B A C
**> C .
**>
**> It is easy to count the number of elements for each level:
**> tapply(X,X,length).
**>
**> Now I have another factor Y, which formed a matrix with X:
**>
**> X| A B B C A C B A C C
**> Y| B B C C C A A A B B
**>
**> I wanna count the number of elements for each of these conditions:
**> when X=A
**> and Y=A; when X=A and Y=B; when X=A and Y=C; when X=B and Y=A; when
**> X=B and
**> Y=B; when X=B and Y=C; when X=C and Y=A; when X=C and Y=B; when X=C
**> and
**> Y=C.
**>
**> The code I have written for this task is too complicated, involving
**> a lot
**> of for loops and if conditions. I believe there's some nice code
**> that can
**> do it far more efficiently. Can anyone give me a hint?
**>
**> Thanks a lot!
**>
**>
*

*> ______________________________________________
*

> R-help@stat.math.ethz.ch mailing list

*> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide!
**> http://www.R-project.org/posting-guide.html
*

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Tue Jun 21 22:58:52 2005

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