Given a PCM or a parameter object, extract an analogical object for a subset of the regimes in the original object.
PCMExtractRegimes(obj, regimes = seq_len(PCMNumRegimes(obj)))
a PCM or a parameter object.
an integer vector; should be a subset or equal to
seq_len(PCMNumRegimes(obj))
(the default).
an object of the same class as obj with a subset of obj's regimes
This is an S3 generic