markov.py 文件源码

def counter_random(counter, filter=None):
    """Return a single random elements from the Counter collection, weighted by count."""
    if filter is not None:
        counter = { k : v for k,v in counter.items() if filter(k) }
    if len(counter) == 0:
        raise Exception("No matching elements in Counter collection")
    seq = list(counter.keys())
    cum = list(itertools.accumulate(list(counter.values()), op.add))
    return seq[bisect.bisect_left(cum, random.uniform(0, cum[-1]))]