Extracts encoded genotype data from binary formatted file.

        :param bytes: array of bytes pulled from the .bed file

        :return: standard python list containing the genotype data

        Only ind_count genotypes will be returned (even if there are
        a handful of extra pairs present).

def extract_genotypes(self, bytes):
        """Extracts encoded genotype data from binary formatted file.

        :param bytes: array of bytes pulled from the .bed file

        :return: standard python list containing the genotype data

        Only ind_count genotypes will be returned (even if there are
        a handful of extra pairs present).

        """
        genotypes = []
        for b in bytes:
            for i in range(0, 4):
                v = ((b>>(i*2)) & 3)
                genotypes.append(self.geno_conversions[v])
        return genotypes[0:self.ind_count]