Pandas 用行值填充列

Question

我有一個 dataframe，看起來像這樣。

key            values
Interface       InterfaceA
State           Up
Line Status     Up
ID              9000
Interface       InterfaceB
State           Down
Line Status     Down
ID              9001

我想把它變成這樣

Interface        State        Line Status       ID
InterfaceA        Up             Up             9000
InterfaceB        Down           Down           9001

我嘗試使用 loc 逐列插入，但是當它到達第二列時

ValueError：無法從重復軸重新索引

出現上述錯誤。

final_df['Interface'] = commands_df.loc[commands_df['key'].str.contains('Interface'), 'values']
final_df['State'] = commands_df.loc[commands_df['key'].str.contains('State'), 'values'] <-- Error starts here

ValueError: cannot reindex from a duplicate axis

Answer 1

df = df.assign(Interface=df[df['key'] == 'Interface']['values']).ffill()
print(df.pivot(index='Interface', columns='key', values='values').drop(columns='Interface'))

印刷：

key           ID Line Status State
Interface                         
InterfaceA  9000          Up    Up
InterfaceB  9001        Down  Down

Answer 2

這是一個可能的解決方案-

import pandas as pd

df = pd.DataFrame(data=['InterfaceA', 'Up', 'Up', 9000, 'InterfaceB', 'Down', 'Down', 9001],
                  index=['Interface', 'State', 'Line Status', 'ID', 'Interface', 'State', 'Line Status', 'ID'])

df = df.T
print(df.groupby(df.columns.values, axis=1).agg(lambda x: x.values.tolist()).sum().apply(pd.Series).T)

     ID   Interface Line Status State
0  9000  InterfaceA          Up    Up
1  9001  InterfaceB        Down  Down

歸功於這個答案

Answer 3

帶有cumcount和unstack的簡單set_index

df_final = df.set_index([df.groupby('key').cumcount(),'key'])['values'].unstack()

Out[423]:
key    ID   Interface Line-Status State
0    9000  InterfaceA          Up    Up
1    9001  InterfaceB        Down  Down

另一種方法是使用pd.crosstab

df_final = pd.crosstab(df.groupby('key')['values'].cumcount(), 
                       df['key'], 
                       df['values'], aggfunc='first')

Out[424]:
key      ID   Interface Line-Status State
row_0
0      9000  InterfaceA          Up    Up
1      9001  InterfaceB        Down  Down