我是MapReduce的新手,我试图在MovieLens 100k数据集中找到电影的平均电影评论。我有一个工作程序,可以找到每部电影的平均评论,但是我只想对评论> 100的电影执行此操作。如何添加条件语句来执行此操作?
from mrjob.job import MRJob
class PopularMovieAvgReview(MRJob):
def mapper(self, key, line):
(userID, movieID, rating, timestamp) = line.split('\t')
yield movieID, float(rating)
def reducer(self, movieID, rating):
total = 0
numElements = 0
for x in rating:
total += x
numElements += 1
yield movieID, total / numElements
if __name__ == '__main__':
PopularMovieAvgReview.run()
如果我理解正确,您想根据给出的等级数限制输出
def reducer(self, movieID, rating):
total = 0
numElements = 0
for x in rating:
total += x
numElements += 1
if numElements > 100:
yield movieID, total / numElements
或者,使用PySpark,您可以汇总,然后过滤收视率金额