python - 如何为以下内容写图归约-6ren

转载作者：行者123 更新时间：2023-12-02 22:08:16

29

4

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center。

已关闭8年。

我有以下数据

Name Year  score
A    1996  84
A    1997  65
A    1996  76
A    1998  78
A    1998  65
B    1998  53
B    1996  98
B    1996  83
B    1996  54

我想要输出如下

Name Year  max_score
A    1996  84
B    1996  98

如何为该工作编写python map reduce代码？

我可以将NAME和YEAR创建为单个键，并按值计分即可。

但是还有其他方法可以解决这个问题。

最佳答案

假设您所有的年数和分数都是正数:

from collections import defaultdict

mapping = defaultdict( lambda: (0,0) )
with open(datafile) as f:
     for line in f:
         name,year,score = line.split()
         try:
            year = int(year)
            score = int(score)
         except ValueError:
            continue

         if score > mapping[name][1]:
            mapping[name] = year,score

或更简洁，但对错误的鲁棒性较低:

from collections import defaultdict

mapping = defaultdict( lambda: (0,0) )
with open(datafile) as f:
     f.readline() #header.  Don't need it.
     for line in f:
         name,year,score = line.split()
         if int(score) > mapping[name][1]:
            mapping[name] = int(year),int(score)

关于python - 如何为以下内容写图归约，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12601843/