def forward_lookup()

in multiset_codec/msbst.py [0:0]

• 16 lines of code
• 6 McCabe index (conditional complexity)

def forward_lookup(multiset, x):
    '''
    Looks up the cumulative (start) and frequency (freq) counts of symbol x.
    '''
    if not multiset:
        raise ValueError("The symbol {} could not be found.".format(x))
    size, y, left, right = multiset
    if x > y:
        start_right, freq = forward_lookup(right, x)
        start = size - right[0] + start_right
    elif x < y:
        start, freq = forward_lookup(left, x)
    else:
        start = left[0] if left else 0
        freq = size - start - (right[0] if right else 0)
    return start, freq