我希望这个 map reduce 作业(下面的代码)输出评分最高的前 10 个产品。它一直给我以下错误信息:
it = izip(iterable, count(0,-1)) # 装饰 类型错误:izip 参数 #1 必须支持迭代。
我认为它与我尝试应用的nlargest 函数有关。
有什么建议吗？
谢谢!
from mrjob.job import MRJob
from mrjob.step import MRStep
from heapq import nlargest
class MostRatedProduct(MRJob):
def steps(self):
return [
MRStep(mapper = self.mapper_get_ratings,
reducer = self.reducer_count_ratings),
MRStep(reducer = self.reducer_find_top10)
]
def mapper_get_ratings(self, _, line):
(userID, itemID, rating, timestamp) = line.split(',')
yield itemID, 1
def reducer_count_ratings(self, itemID, ratingCount):
yield None, (sum(ratingCount), itemID)
def top_10(self, ratingPair):
for ratingTotal, itemID in ratingPair:
top_rated = nlargest(10, ratingTotal)
for top_rated in ratingTotal:
return (ratingTotal, itemID)
def reducer_find_top10(self, key, ratingPair):
ratingTotal, itemID = self.top_10(ratingPair)
yield ratingTotal, itemID
if __name__ == '__main__':
MostRatedProduct.run()
请您参考如下方法:
使用 mrjob 库，您可以在 python 中执行相同的操作:-
#Write a Code to print the top 5 word - occurences
#Import Dependencies
from mrjob.job import MRJob
from mrjob.step import MRStep
class MRWordCount(MRJob):
def steps(self):
return [MRStep(mapper=self.mapper,reducer=self.reducer),MRStep(reducer = self.secondreducer)]
def mapper(self,_,lines):
words = lines.split()
for word in words:
yield word.lower(),1
def reducer(self,key,values):
yield None,('%04d'%int(sum(values)),key)
def secondreducer(self,key,values):
self.alist = []
for value in values:
self.alist.append(value)
self.blist = []
for i in range(5):
self.blist.append(max(self.alist))
self.alist.remove(max(self.alist))
for i in range(5):
yield self.blist[i]
if __name__ == '__main__':
MRWordCount.run()
