def get_fraction(lsnp1, lsnp2):
    """Return the fraction of reads supporting region1."""
    reg1_fraction = []
    for index in range(len(lsnp1)):
        sumdepth = lsnp1[index] + lsnp2[index]
        if sumdepth == 0:
            reg1_fraction.append(0)
        else:
            reg1_fraction.append(float(lsnp1[index]) / float(sumdepth))
    return reg1_fraction