Get a Keras generator from a data filter

Noise filters can be applied during training (in denoising autoencoders), for this a generator is used to get data batches.

# S3 method for ruta_filter
to_keras(x, data, batch_size, ...)

Arguments

x	Filter object
data	Matrix where the filter will be applied
batch_size	Size of the sample (for the training stage)
...	Additional parameters, currently unused