group
  is the generic method.
xcmsSet-class objectxcmsSet object with peak group assignments and statistics.
    group(object, ...)
  
method argument. For example to use the density-based
  approach described by Smith et al (2006) one would use:
  group(object, method="density"). This is also the default.  Further arguments given by ... are
  passed through to the function implementing
  the method.
  A character vector of nicknames for the
  algorithms available is returned by
  getOption("BioC")$xcms$group.methods.
  If the nickname of a method is called "mzClust",
  the help page for that specific method can
  be accessed with ?group.mzClust.
group.density
  group.mzClust
  group.nearest
  xcmsSet-class,