pandas中的Dataframe sub

Question

我试图在同一数据帧中用另一列减去一列，但我只有nan

输入数据帧diff：

     circulating_supply_2
currency                      
BCH               1.822555e+07
BTC               1.816325e+07
ETH               1.092969e+08
QASH              3.500000e+08
XRP               4.365378e+10      
 circulating_supply_1
currency                      
BCH               1.823258e+07
BTC               1.817038e+07
ETH               1.093499e+08
QASH              3.500000e+08
XRP               4.365378e+10

我的代码：

diff = diff.iloc[:,-1:].sub(diff.iloc[:,-2:-1])

输出：

          circulating_supply_1  circulating_supply_2
currency                                            
BCH                        NaN                   NaN
BTC                        NaN                   NaN
ETH                        NaN                   NaN
QASH                       NaN                   NaN
XRP                        NaN                   NaN

请提供任何帮助。

Answer 1

diff['circulating_supply_2'] - diff['circulating_supply_1']