lec8.4-getRatios.py

# lec8.4-getRatios.py
# edX MITx 6.00.1x
# Introduction to Computer Science and Programming Using Python
# Lecture 8, video 4

# Exceptions as flow control

def getRatios(v1, v2):
    """ Assumes: v1 and v2 are lists of equal length of numbers
        ReturnL a list containing the meaningful values of
        v1[i]/v2[i]"""

    ratios = []
    for index in range(len(v1)):
        try:
            ratios.append(v1[index]/float(v2[index]))
        except ZeroDivisionError:
            ratios.append(float('NaN')) # NaN = Not a numbers
        except:
            raise ValueError('getRatios called with a bad arg')
    return ratios


try:
    print getRatios([1.0, 2.0, 7.0, 6.0], [1.0, 2.0, 0.0, 3.0])
    print getRatios([], [])
    print getRatios([1.0, 2.0], [3.0])
except ValueError, msg:
    print msg