logit_rules.py 文件源码

def log_multinomial_coefficient(list_of_primitive_rules):
    """ 
    Count copies of each primitive and calculate a log multinomial coefficient.
~    
    """
    list_of_tuples = [p.as_tuple() for p in list_of_primitive_rules]
    counts = dict.fromkeys(set(list_of_tuples),0)
    for t in list_of_tuples:
        counts[t] += 1
    N = len(list_of_primitive_rules)
    v = np.array(counts.values())
    return gammaln(N+1)-np.sum(gammaln(v+1))