我想创建一个mapreduce程序,它的reduce接收按值排序的k-v对。我使用的是mrjob,它的sort\u values参数似乎非常适合这个任务。将此参数设置为true后,reducer输入没有排序,例如,我得到以下结果(考虑到a应该在x之前):
"ES" ["X", 3]
"ES" ["A", "Spain"]
我使用的是python2.7.5、mrjob==0.6.1和hadoop。程序的本地执行给了我:
"ES" ["A", "Spain"]
"ES" ["X", 1]
"ES" ["X", 2]
这是正确的。但是hadoop的执行提供了:
"ES" ["X", 3]
"ES" ["A", "Spain"]
我的代码是:
import sys, os, re
from mrjob.job import MRJob
from mrjob.step import MRStep
class MRJoin(MRJob):
SORT_VALUES = True
def mapper(self, _, line):
splits = line.rstrip("\n").split(",")
if len(splits) == 2: # countries
symbol = 'A' # countries before clients
country2digit = splits[1]
yield country2digit, (symbol, splits[0])
else: # clients
symbol = 'X'
country2digit = splits[2]
if splits[1]=='bueno':
yield country2digit,(symbol, 1)
def combiner(self,key, values):
bueno=0
for value in values:
if value[0] == 'A':
yield key, ('A', value[1])
else:
bueno=bueno + 1
if bueno > 0:
yield key, ('X', bueno)
def reducerSimple(self, key, values):
for value in values:
yield key,value
def steps(self):
return [
MRStep(mapper=self.mapper
,combiner=self.combiner
,reducer=self.reducerSimple)
]
if __name__ == '__main__':
MRJoin.run()
我像这样运行上面的代码:
python mrjob-p2.py/media/notebooks/clients.csv/media/notebooks/countries.csv-r hadoop
它给出:
"ES" ["X", 3]
"ES" ["A", "Spain"]
...
"GN" ["A", "Guinea"]
"GN" ["X", 1]
...
es键(和其他少数键)的值不会被排序,但对于其他键,它们会被排序。
我期望(如果对值进行了排序,那么a应该在x之前):
"ES" ["A", "Spain"]
"ES" ["X", 3]
如果我在本地运行:
python mrjob-p2.py/media/notebooks/clients.csv/media/notebooks/countries.csv-r local
然后我得到:
"ES" ["A", "Spain"]
"ES" ["X", 1]
"ES" ["X", 2]
...
"GN" ["A", "Guinea"]
"GN" ["X", 1]
...
这是正确的。
有人知道如何把这些值排序吗?
谢谢:)
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