get genotype IDs. 
        Optionally the indices for loading subgroups the genotype IDs for all people
        can be given in one out of three ways: 
        - 0-based indexing (i0-i1)
        - position (pos0-pos1 on chrom)
        - cumulative position (pos_cum0-pos_cum1)
        If all these are None (default), then all genotypes are returned

        Args:
            i0:         genotype index based selection (start index)
            i1:         genotype index based selection (stop index)
            pos0:       position based selection (start position)
            pos1:       position based selection (stop position)
            chrom:      position based selection (chromosome)
            pos_cum0:   cumulative position based selection (start position)
            pos_cum1:   cumulative position based selection (stop position)
           
        Returns:
            ID:         scipy.array of genotype IDs (e.g. rs IDs)

def getGenoID(self,i0=None,i1=None,pos0=None,pos1=None,chrom=None,pos_cum0=None,pos_cum1=None):
        """get genotype IDs. 
        Optionally the indices for loading subgroups the genotype IDs for all people
        can be given in one out of three ways: 
        - 0-based indexing (i0-i1)
        - position (pos0-pos1 on chrom)
        - cumulative position (pos_cum0-pos_cum1)
        If all these are None (default), then all genotypes are returned

        Args:
            i0:         genotype index based selection (start index)
            i1:         genotype index based selection (stop index)
            pos0:       position based selection (start position)
            pos1:       position based selection (stop position)
            chrom:      position based selection (chromosome)
            pos_cum0:   cumulative position based selection (start position)
            pos_cum1:   cumulative position based selection (stop position)
           
        Returns:
            ID:         scipy.array of genotype IDs (e.g. rs IDs)
        """
        #position based matching?
        if (i0 is None) and (i1 is None) and ((pos0 is not None) & (pos1 is not None) & (chrom is not None)) or ((pos_cum0 is not None) & (pos_cum1 is not None)):
            i0,i1=self.getGenoIndex(pos0=pos0,pos1=pos1,chrom=chrom,pos_cum0=pos_cum0,pos_cum1=pose_cum1)
        if "genotype_id" in list(self.geno.keys()):
            if (i0 is not None) & (i1 is not None):
                return self.geno["genotype_id"][i0:i1]
            else:
                return self.geno["genotype_id"][i0:i1]
        else:
            if (i0 is not None) & (i1 is not None):
                return SP.arange(i0,i0)
            else:
                return SP.arange(self.genoM.shape[1])
        pass