Pandas从同一数据框中减去2行

Question

如何从以下数据帧（df）中的另一行中减去一行：

RECL_LCC          1          2          3
RECL_LCC  35.107655  36.015210  28.877135
RECL_PI   36.961519  43.499506  19.538975

我想做的事情是：

df['Difference'] = df['RECL_LCC']-df['RECL_PI']

但这给了我们：

*** KeyError: 'RECL_LCC'

Answer 1

可以使用df.loc按索引值选择行：

In [98]: df.loc['Diff'] = df.loc['RECL_LCC'] - df.loc['RECL_PI']

In [99]: df
Out[99]: 
RECL_LCC          1          2          3
RECL_LCC  35.107655  36.015210  28.877135
RECL_PI   36.961519  43.499506  19.538975
Diff      -1.853864  -7.484296   9.338160