Python和集体智慧：第2章：推荐项目

Question

我正在学习如何智力的集体作品，我在练习中第2章这里做例子recommendations.py问题是链接：

http://cdn.jampad.net/Library/collectiveintelligence/#calibre_link-201

当我复制并粘贴此代码：

# Gets recommendations for a person by using a weighted average 
# of every other user's rankings 
def getRecommendations(prefs,person,similarity=sim_pearson): 
    totals={} 
    simSums={} 
    for other in prefs: 
# don't compare me to myself 
if other==person: continue 
sim=similarity(prefs,person,other) 

# ignore scores of zero or lower 
if sim<=0: continue 
for item in prefs[other]: 

    # only score movies I haven't seen yet 
    if item not in prefs[person] or prefs[person][item]==0: 
    # Similarity * Score 
    totals.setdefault(item,0)totals[item]+=prefs[other][item]*sim 
    # Sum of similarities 
    simSums.setdefault(item,0) 
    simSums[item]+=sim 

# Create the normalized list 
rankings=[(total/simSums[item],item) for item,total in totals.items()] 

# Return the sorted list 
rankings.sort() 
rankings.reverse() 
return rankings 

进入我的recommendations.py文件，当我重新加载该文件，我收到一个语法错误。

>>> reload(recommendations) 
Traceback (most recent call last): 
File "<stdin>", line 1, in <module> 
File "recommendations.py", line 100 
    totals.setdefault(item,0)totals[item]+=prefs[other][item]*sim 
          ^

SyntaxError: invalid syntax 

这是我收到的信息。我不确定我是否正确地复制并粘贴了代码，或者如果给定的代码行是错误的。

Answer 1

这...

totals.setdefault(item,0)totals[item]+=prefs[other][item]*sim 

，就是要两条线：

totals.setdefault(item,0) 
totals[item]+=prefs[other][item]*sim