Calculate ratio with Python and Numpy.

ratio.py

#calculates r for height and width
def ratio(a, b):
    a = float(a)
    b = float(b)
    if b == 0:
        return a
    return ratio(b, a % b)

#returns a string with ratio for height and width
def get_ratio(a, b):
    r = ratio(a, b)
    return "%s" % float((a/r) / (b/r))