'Get the group parameter values.'

def par(self, parname):

    if _is_int(parname):
        result = self.field(parname)
    else:
        indx = self._unique[parname.upper()]
        if (len(indx) == 1):
            result = self.field(indx[0])
        else:
            result = self.field(indx[0]).astype('f8')
            for i in indx[1:]:
                result += self.field(i)
    return result
