查找字符串间的概率

Question

我想找到来自文件的数据概率。我已经测试了一种方法，首先找到共同出现，然后找到总计数。数据集可以如下给出：

director     Actor       genere
Scorseses    DeNiro      crime
Coppola      DeNiro      crime
Hitchcock    Stewart     Thriller
Hitchcock    Grant       Thriller 
Koster       Grant        Comedy
Koster       Stewart      Comedy

代码是：

 def find_prob(c,d):
     columns=defaultdict(list)
     with open('function.csv') as f:
         reader=csv.DictReader(f)
         for row in reader:
             for (k,v) in row.items():
                columns[k].append(v)
         print(columns)

 ab=[0,1]
 for k in columns:
    for i in ab:
         if(columns[k][i]==d):
                words_count=collections.Counter(columns[k])
                a=words_count[d]

 rdr = csv.reader(open(r"function.txt"))
 c1 = collections.Counter((x, y) for  a,b,_ in rdr for x, y in product(a.split(","),b.split(",")))
 xy=c1[c,d]
 print(xy)
 print(a)
 prob= (xy/a)
 print(prob)

我想要一种更通用的方法来找到价值的共同出现？