分组和计算频率， pandas [英] Grouping and Computing Frequency ,Pandas

问题描述

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']})

，我需要将观察结果归类，即所有神奇宝贝类型及其各自的名称.而且我需要添加另一列，该列具有类型中名称出现的频率.看起来应该像:

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 :

Type         Name     Frequency   
Pokemon      Jerry        3 
             Mudkip       2    

Bird         Pigeon       2  
           Flappy Bird    1  

我用过:

data2 = df.groupby(['Type']) 

但这并没有按照需要的方式进行分组.
请帮忙.

but that doesn't group it the way it needs to be.
Please help.

推荐答案

我认为您想同时对类型"和名称"进行分组:

I think you want to group on both 'Type' and 'Name':

print df.groupby(['Type','Name']).size()

Type     Name       
Bird     Flappy Bird    1
         Pigeon         2
Pokemon  Jerry          3
         Mudkip         2

或者如果重要的是要有名为"Frequency"的列，则可以执行以下操作:

Or if it is important to have the column named 'Frequency', you could do something like the following:

print df.groupby(['Type','Name'])['Type'].agg({'Frequency':'count'})

                     Frequency
Type    Name                  
Bird    Flappy Bird          1
        Pigeon               2
Pokemon Jerry                3
        Mudkip               2

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