Message-ID: <3DF756A7.269929C1@yorku.ca>
Date: 2002-12-11T16:16:05Z
From: Michael Friendly
Subject: Excluding levels in table and xtabs
I'm trying to form contingincy tables among a set of character variables
which were read from a .csv file and
have missing represented as "". I want to exclude the missing levels
from the table.
> levels(CPIC)
[1] "" "N" "Y"
> levels(Manix)
[1] "" "N" "Y"
> xtabs(~CPIC + Manix, exclude=c("",NA))
Manix
CPIC N Y
272 4 15
N 154 2812 1472
Y 158 466 4870
> table(CPIC, Manix, exclude=c("",NA))
Manix
CPIC N Y
272 4 15
N 154 2812 1472
Y 158 466 4870
The only way I can exclude them is by
t <- table(CPIC, Manix)
t <- t[-1,-1]
that's not to hard in this case, but my application is to a much
larger table where this gets unweildly.
--
Michael Friendly friendly at yorku.ca
York University http://www.math.yorku.ca/SCS/friendly.html
Psychology Department
4700 Keele Street Tel: (416) 736-5115 x66249
Toronto, Ontario, M3J 1P3 Fax: (416) 736-5814