协作型过滤（1）：用户偏好数据存储

1.用户偏好数据存储

用嵌套的字典表达不同人及其偏好，可以很方便地对其进行查询、修改。当数据相当大时，则选择奖数据存入数据库中。

#影评者及其对几部电影的评价
critics={'Lisa Rose': {'Lady in the Water': 2.5, 'Snakes on a Plane': 3.5,
'Just My Luck': 3.0, 'Superman Returns': 3.5, 'You, Me and Dupree': 2.5,
'The Night Listener': 3.0},
'Gene Seymour': {'Lady in the Water': 3.0, 'Snakes on a Plane': 3.5,
'Just My Luck': 1.5, 'Superman Returns': 5.0,'The Night Listener': 3.0, 
'You, Me and Dupree': 3.5},
'Michael Phillips': {'Lady in the Water': 2.5, 'Snakes on a Plane': 3.0,
'Superman Returns': 3.5, 'The Night Listener': 4.0},
'Claudia Puig': {'Snakes on a Plane': 3.5,'Just My Luck': 3.0,
'The Night Listener': 4.5,'Superman Returns': 4.0, 
'You, Me and Dupree': 2.5},
'Mick LaSalle': {'Lady in the Water': 3.0, 'Snakes on a Plane': 4.0,
'Just My Luck': 2.0, 'Superman Returns': 3.0, 'The Night Listener': 3.0,
'You, Me and Dupree': 2.0},
'Jack Matthews': {'Lady in the Water': 3.0, 'Snakes on a Plane': 4.0,
'The Night Listener': 3.0,'Superman Returns': 5.0, 'You, Me and Dupree': 3.5},
'Toby': {'Snakes on a Plane': 4.5,'You, Me and Dupree': 1.0,'Superman Returns': 4.0}}

查询或修改操作，上述文件应保存在启动Python时的当前文件，或者保存在python/lib目录下：

from recommendations import critics
print  critics['Lisa Rose'][‘Lady in the Water’]
critics['Lisa Rose'][‘Lady in the Water’]=4.5
print  critics['Lisa Rose'][‘Lady in the Water’]
print  critics['Lisa Rose']