preTrainDArch-DArch-method: Pre-trains a 'DArch' network
In darch: Package for Deep Architectures and Restricted Boltzmann Machines

Pre-trains a DArch network

## S4 method for signature 'DArch'
preTrainDArch(darch, dataSet, dataSetValid = NULL,
  numEpochs = 1, numCD = 1, lastLayer = 0, isClass = F,
  consecutive = T, ...)

`darch`	A instance of the class `DArch`.
`dataSet`	`DataSet` to be used for training.
`dataSetValid`	`DataSet` to be used for validation.
`numEpochs`	The number of epochs
`numCD`	The number of CD iterations
`lastLayer`	Numeric indicating after which layer to stop training.
`isClass`	Whether to test pre-trained networks against target data
`consecutive`	Whether to train RBMs consecutively instead of each one epoch at a time.
`...`	Additional parameters for the function `trainRBM`