Pandas中基于DataFrame特征的计算？

Question

我有如下的DataFrame：

df = pd.DataFrame({"ID" : ["1", "2", "2", "1", "3"],
                    "currency" : ["GBP", "GBP", "GBP", "CHF", "EUR"],
                    "amount" : [100, 200, 300, 400, 500]})

我需要计算一下：

1. New1 =与英镑货币的协议数量
2. New2=与英镑货币

的协议数量

我需要的结果如下：

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Answer 1

我们可以做过滤然后groupby和reindex

out = df.loc[df.currency=='GBP'].groupby(['ID']).amount.agg(['count','sum']).reindex(df.ID.unique())
Out[210]: 
    count    sum
ID              
1     1.0  100.0
2     2.0  500.0
3     NaN    NaN

Answer 2

你可以试试这个-

import pandas as pd

df = pd.DataFrame({"ID" : ["1", "2", "2", "1", "3"],
                    "currency" : ["GBP", "GBP", "GBP", "CHF", "EUR"],
                    "amount" : [100, 200, 300, 400, 500]})

>>> pd.pivot_table(df.loc[df.currency=='GBP'],index=["ID"],aggfunc={'currency':'count','amount':'sum'}).reindex(df.ID.unique()).reset_index()
   
ID  amount  currency                
1    100.0       1.0
2    500.0       2.0
3      NaN       NaN