[Rd] Anomaly with unique and match
Terry Therneau
therneau at mayo.edu
Wed Mar 9 15:48:10 CET 2011
I stumbled onto this working on an update to coxph. The last 6 lines
below are the question, the rest create a test data set.
tmt585% R
R version 2.12.2 (2011-02-25)
Copyright (C) 2011 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
Platform: x86_64-unknown-linux-gnu (64-bit)
# Lines of code from survival/tests/singtest.R
> library(survival)
Loading required package: splines
> test1 <- data.frame(time= c(4, 3,1,1,2,2,3),
+ status=c(1,NA,1,0,1,1,0),
+ x= c(0, 2,1,1,1,0,0))
>
> temp <- rep(0:3, rep(7,4))
>
> stest <- data.frame(start = 10*temp,
+ stop = 10*temp + test1$time,
+ status = rep(test1$status,4),
+ x = c(test1$x+ 1:7, rep(test1$x,3)),
+ epoch = rep(1:4, rep(7,4)))
>
> fit1 <- coxph(Surv(start, stop, status) ~ x * factor(epoch), stest)
## New lines
> temp1 <- fit1$linear.predictor
> temp2 <- as.matrix(temp1)
> match(temp1, unique(temp1))
[1] 1 2 3 4 4 5 6 7 7 7 6 6 6 8 8 8 6 6 6 9 9 9 6 6
> match(temp2, unique(temp2))
[1] 1 2 3 4 4 5 6 7 7 7 6 6 6 NA NA NA 6 6 6 8 8 8
6 6
-----------------------
I've solved it for my code by not calling match on a 1 column vector.
In general, however, should I be using some other paradym for this "map
to unique" operation? For example match(as.character(x),
unique(as.character(x)) ?
Terry T
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