[R] nnet behaving oddly

[Rajarshi Guha]

Hi,
  I was trying to use the nnet library and am not sure of whats going
on. I am calling the nnet function as:

 n <- nnet(x,y,size=3,subset=sets[[1]], maxit=200)

Where x is a 272x4 matrix of observations (examples) and y is a 272x1
matrix of target values. However when I look at nnet$residuals they are
off by two orders of magnitude (compared to the output from neural
network code that I already have). Looking at nnet$fitted.values shows
all the values to be 1 (whereas my target values range from 0 to 150).

Am I making an obvious mistake in the way I'm calling the function? Is
the fact that n$fitted.values is all 1's indicating that the NN is doing
a classification? If so how can I make it do quantitation?

The man page mentions that if the response is a factor then it defaults
to quantitation. However my y matrix just contain numbers - so it
should'nt be doing classification.

Any pointers would be appreciated.

Thanks,

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Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
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Psychology is merely producing habits out of rats.