DATA MINING
Desktop Survival Guide by Graham Williams |
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Tutorial Example |
The nnet package provides algorithms for feed-forward neural networks with a single hidden layer, and for multinomial log-linear models.
> library(nnet) > ?nnet # See example there |
Consider a two-class problem. Build a neural network with
> |
The Rarg[]linout= argument ensures the model predicts a linear value, rather than a logistic value.
The average Matthew Correlation Coeffience can be used to gauge the performance of the neural network. The highr the value the better.
For an unbalanced class, for example where the ratio of class A to
class B is about 3:100, we might decide to weight the
under-represented class:
> sample.nn <- nnet(....... weights=ifelse(ds$class=="A", 100/3, 1) |
Note that we must do any scaling of continuous before using nnet since it is not done inside nnet (unlike ksvm).