# -*- coding: UTF8 -*-
import sys
import copy
def init_pass(T):
C = {}
for t in T:
for i in t:
if i in C.keys():
C[i] += 1
else:
C[i] = 1
return C
def candidate_gen(F):
C = []
k = len(F[0]) + 1
for f1 in F:
for f2 in F:
if f1[k-2] < f2[k-2]:
c = copy.copy(f1)
c.append(f2[k-2])
flag = True
for i in range(0,k-1):
s = copy.copy(c)
s.pop(i)
if s not in F:
flag = False
break
if flag and c not in C:
C.append(c)
return C
def compare_list(A,B):
if len(A) <= len(B):
for a in A:
if a not in B:
return False
else:
for b in B:
if b not in A:
return False
return True
def apriori(T, minsup):
C = []
init = init_pass(T)
keys = init.keys()
keys.sort()
C.append(keys)
n = len(T)
F = [[]]
for f in C[0]:
if init[f]*1.0/n >= minsup:
F[0].append([f])
k = 1
while F[k-1] != []:
C.append(candidate_gen(F[k-1]))
F.append([])
for c in C[k]:
count = 0;
for t in T:
if compare_list(c,t):
count += 1
if count*1.0/n >= minsup:
F[k].append(c)
k += 1
U = []
for f in F:
for x in f:
U.append(x)
return U
T = [['A','B','C','D'],['B','C','E'],['A','B','C','E'],['B','D','E'],['A','B','C','D']]
F = apriori(T, 0.9)
print F
