def sort_precursor(c, loci):
<EOL>data_loci = [[x, loci[x].chr, int(loci[x].start), int(loci[x].end), loci[x].strand, len(c.loci2seq[x])] for x in list(c.loci2seq.keys())]<EOL>data_loci = sorted(data_loci, key=itemgetter(<NUM_LIT:5>), reverse=True)<EOL>return data_loci<EOL>
Sort loci according to number of sequences mapped there.