AW: [R] Error in randomForest.default(m, y, ...) : negative length vectors are not allowed

[Christian Schulz]

Hmmm, thanks for your suggestions i'm in the
same opinion with any subsetting problem, but curious is
that my model i.e. with library(gbm) or simple lm works,
because my task is to find out the weights/importance values
for the attributes and i would like compare the results between
the randomForest classifier and a linear approach.

I check it with your suggestions and code snippets in detail
and feedback you the problem, if i found the solution.

regards,Christian



-----Ursprüngliche Nachricht-----
Von: Wiener, Matthew [mailto:matthew_wiener at merck.com]
Gesendet: Mittwoch, 3. Dezember 2003 17:26
An: 'Christian Schulz'; r-help at stat.math.ethz.ch
Betreff: RE: [R] Error in randomForest.default(m, y, ...) : negative
lengt h vectors are not allowed


Christian --

You don't provide enough information (like a call) to answer this.  I
suspect, though, that you may be subsetting in a way that passes
randomForest no data.

I'm not aware offhand of an easy way to get this error from randomForest.  I
tried creating some data superficially similar to yours to see whether
something would break if there were only a single value in the variable to
be explained, but everything worked fine (though it does give a reasonable
warning).

> test.dat <- data.frame(a = rep(0, 1000), b = runif(1000), c = sample(0:1,
1000, replace = TRUE, p = c(.8, .2))
> t8 <- randomForest(a ~ b + c, data = test.dat)
Warning message:
The response has five or fewer unique values.  Are you sure you want to do
regression? in: randomForest.default(m, y, ...)
> test.dat[sample(1:1000, 100),"a"] <- runif(100, 1, 200)
> t8 <- randomForest(a ~ b + c, data = test.dat)

Some other generated data might come up with the error, but I'd bet on the
subsetting problem.

Hope this helps,  -Matt

Matthew Wiener
RY84-202
Applied Computer Science & Mathematics Dept.
Merck Research Labs
126 E. Lincoln Ave.
Rahway, NJ 07065
732-594-5303

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Christian Schulz
Sent: Wednesday, December 03, 2003 9:42 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Error in randomForest.default(m, y, ...) : negative length
vectors are not allowed


Hi,

what i'm doing wrong?
I'm using a data.frame with ~ 90.000 instances
and 7 attributes, 5 are binary recoded
1 independend variable are a real one
and the target is a real one,too.

The distributions are not very skewed in the dummy variables
,but in the real variables are ~ 60.000
zero values instances, but zero means
no money is payed and is a important value!

Many thanks for help & suggestions,
regards,christian

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