在 Pandas Grouby 数据框上建立索引给出错误
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Indexing on Pandas Grouby Data frame Gives error
提问by function
I have a Pandas GroupBy Data frame named ratings_by_titlethat looks like the following:
我有一个名为ratings_by_title的 Pandas GroupBy 数据框，如下所示：
title
,000,000 Duck (1971) 37
'Night Mother (1986) 70
'Til There Was You (1997) 52
'burbs, The (1989) 303
...And Justice for All (1979) 199
1-900 (1994) 2
10 Things I Hate About You (1999) 700
101 Dalmatians (1961) 565
101 Dalmatians (1996) 364
12 Angry Men (1957) 616
I am trying to filter out the titles having a rating of >=250 so,
我试图过滤掉评分 >=250 的标题，所以，
I tried the following active_titles = ratings_by_title.index[ratings_by_title >= 250]
我尝试了以下 active_titles = ratings_by_title.index[ratings_by_title >= 250]
But,This gives an error in iPython saying
但是，这在 iPython 中给出了一个错误说
AttributeError: Cannot access attribute 'index' of 'DataFrameGroupBy' objects, try using the 'apply' method
AttributeError：无法访问“DataFrameGroupBy”对象的属性“index”，请尝试使用“apply”方法
Could somebody help me understand what's going on?
有人可以帮助我了解发生了什么吗？
回答by function
Got it ... when grouping by should add the size method
明白了......分组时应该添加大小方法
eg) ratings_by_title = data.groupby('title').size()
例如) ratings_by_title = data.groupby('title').size()
This solved the issue!!
这就解决了问题！！
Now i can index like:
现在我可以索引如下：
active_ratings = ratings_by_title.index[ratings_by_title >= 250]
active_ratings = ratings_by_title.index[ ratings_by_title >= 250]
