分组和计算频率，Pandas
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Grouping and Computing Frequency ,Pandas
提问by Hypothetical Ninja
I have a dataframe :
我有一个数据框：
df = pd.DataFrame({'Type' : ['Pokemon', 'Pokemon', 'Bird', 'Pokemon', 'Bird', 'Pokemon', 'Pokemon', 'Bird'],'Name' : ['Jerry', 'Jerry', 'Flappy Bird', 'Mudkip','Pigeon', 'Mudkip', 'Jerry', 'Pigeon']})
and i need to group the observations w.r.t their types i.e all pokemon types together with their respective names . And i need to add another column which has the frequency of occurrence of the names in the types. It should look like :
我需要将观察结果与它们的类型（即所有口袋妖怪类型及其各自的名称）分组。我需要添加另一列，该列具有类型中名称的出现频率。它应该看起来像：
Type Name Frequency
Pokemon Jerry 3
Mudkip 2
Bird Pigeon 2
Flappy Bird 1
I used :
我用了 ：
data2 = df.groupby(['Type'])
but that doesn't group it the way it needs to be.
Please help.
但这并没有按照它需要的方式对其进行分组。
请帮忙。
回答by Karl D.
I think you want to group on both 'Type' and 'Name':
我认为您想对“类型”和“名称”进行分组：
print df.groupby(['Type','Name']).size()
Type Name
Bird Flappy Bird 1
Pigeon 2
Pokemon Jerry 3
Mudkip 2
Or if it is important to have the column named 'Frequency', you could do something like the following:
或者，如果将列命名为“频率”很重要，您可以执行以下操作：
print df.groupby(['Type','Name'])['Type'].agg({'Frequency':'count'})
Frequency
Type Name
Bird Flappy Bird 1
Pigeon 2
Pokemon Jerry 3
Mudkip 2
