Thanks Joe,
It works well. How can I expand the output of z to include all other classes
from 1 to nclass
Right now I the output is:> z
truth
classified 4 5 8 10
1 1 1 1 0
4 6 10 8 0
10 1 0 1 1> Is it possible to have something like:
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
[1,] 0 0 0 1 1 0 0 1 0 0 0 0
[2,] 0 0 0 0 0 0 0 0 0 0 0 0
[3,] 0 0 0 0 0 0 0 0 0 0 0 0
[4,] 0 0 0 6 10 0 0 8 0 0 0 0
[5,] 0 0 0 0 0 0 0 0 0 0 0 0
[6,] 0 0 0 0 0 0 0 0 0 0 0 0
[7,] 0 0 0 0 0 0 0 0 0 0 0 0
[8,] 0 0 0 0 0 0 0 0 0 0 0 0
[9,] 0 0 0 0 0 0 0 0 0 0 0 0
[10,] 0 0 0 1 0 0 0 1 0 1 0 0
[11,] 0 0 0 0 0 0 0 0 0 0 0 0
[12,] 0 0 0 0 0 0 0 0 0 0 0 0
Thanks
"Crombie, Joe" <Joe.Crombie@brs.gov.au> a écrit : Hi Louis,
You could try this:
# find the index of the maximum value in each row of _data_, #
disregarding the last column classified <-
apply(data[,-(nclass+1)],1,which.max)
## or, if the maximum may be repeated:
classified <- apply(data[,-(nclass+1)], 1, FUN = function(x) which(x
=max(x)))
# the variable _truth_ is just the last column of _data_ ?
truth <- data[,nclass + 1]
?table
z <- table(classified, truth)
HTH Joe
Joe Crombie
Biosecurity and Information Sciences
Bureau of Rural Science
Canberra Australia
e: joe.crombie@brs.gov.au
-----Original Message-----
From: r-help-bounces@r-project.org [mailto:r-help-bounces@r-project.org]
On Behalf Of Louis Martin
Sent: Friday, 21 December 2007 11:37 AM
To: R-help@r-project.org
Subject: [R] using apply to loop
Hi,
I am running the following loop, but it takes hours to run as n is big.
Is there any way "apply" can be used? Thanks.
### Start
nclass <- dim(data)[[2]] - 1
z <- matrix(0, ncol = nclass, nrow = nclass)
n <- dim(data)[[1]]
x <- c(1:nclass)
# loop starts
for(loop in 1:n) {
r <- data[loop, 1:nclass]
classified <- x[r == max(r)]
truth <- data[loop, nclass + 1]
z[classified, truth] <- z[classified, truth] + 1
}
# loop ends
---------------------------------
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