#-*-?coding:?utf-8?-*-
‘‘‘
Created?on?2015-06-22
@author:?Lockvictor
‘‘‘
import?sys
import?random
import?math
import?os
from?operator?import?itemgetter


random.seed（0）


class?ItembasedCF（object）:
????‘‘‘?TopN?recommendation?-?Item?based?Collaborative?Filtering?‘‘‘

????def?__init__（self）:
????????self.trainset?=?{}
????????self.testset?=?{}

????????self.n_sim_movie?=?20
????????self.n_rec_movie?=?10

????????self.movie_sim_mat?=?{}
????????self.movie_popular?=?{}
????????self.movie_count?=?0

????????print（‘Similar?movie?number?=?%d‘?%?self.n_sim_movie?file=sys.stderr）
????????print（‘Recommended?movie?number?=?%d‘?%
??????????????self.n_rec_movie?file=sys.stderr）

????@staticmethod
????def?loadfile（filename）:
????????‘‘‘?load?a?file?return?a?generator.?‘‘‘
????????fp?=?open（filename?‘r‘）
????????for?i?line?in?enumerate（fp）:
????????????yield?line.strip（‘\r\n‘）
????????????if?i?%?100000?==?0:
????????????????print?（‘loading?%s（%s）‘?%?（filename?i）?file=sys.stderr）
????????fp.close（）
????????print?（‘load?%s?succ‘?%?filename?file=sys.stderr）

????def?generate_dataset（self?filename?pivot=0.7）:
????????‘‘‘?load?rating?data?and?split?it?to?training?set?and?test?set?‘‘‘
????????trainset_len?=?0
????????testset_len?=?0

????????for?line?in?self.loadfile（filename）:
????????????user?movie?rating?_?=?line.split（‘::‘）
????????????#?split?the?data?by?pivot
????????????if?random.random（）?????????????????self.trainset.setdefault（user?{}）
????????????????self.trainset[user][movie]?=?int（rating）
????????????????trainset_len?+=?1
????????????else:
????????????????self.testset.setdefault（user?{}）
????????????????self.testset[user][movie]?=?int（rating）
????????????????testset_len?+=?1

????????print?（‘split?training?set?and?test?set?succ‘?file=sys.stderr）
????????print?（‘train?set?=?%s‘?%?trainset_len?file=sys.stderr）
????????print?（‘test?set?=?%s‘?%?testset_len?file=sys.stderr）

????def?calc_movie_sim（self）:
????????‘‘‘?calculate?movie?similarity?matrix?‘‘‘
????????print（‘counting?movies?number?and?popularity...‘?file=sys.stderr）

????????for?user?movies?in?self.trainset.items（）:
????????????for?movie?in?movies:
????????????????#?count?item?popularity
????????????????if?movie?not?in?self.movie_popular:
????????????????????self.movie_popular[movie]?=?0
????????????????self.movie_popular[movie]?+=?1

????????print（‘count?movies?number?and?popularity?succ‘?file=sys.stderr）

????????#?save?the?total?number?of?movies
????????self.movie_count?=?len（self.movie_popular）
????????print（‘total?movie?number?=?%d‘?%?self.movie_count?file=sys.stderr）

????????#?count?co-rated?users?between?items
????????itemsim_mat?=?self.movie_sim_mat
????????print（‘building?co-rated?users?matrix...‘?file=sys.stderr）

????????for?user?movies?in?self.trainset.items（）:
????????????for?m1?in?movies:
????????????????for?m2?in?movies:
????????????????????if?m1?==?m2:
?????????