日期时间索引筛选和值更改

Question

NaN0.0<1.0>

日期	COL_1	COL_2
2017-04-21	0.0
2017-04-24	1.0
2017-04-25	0.0

IIUC:

df.loc[(df.index == df.index.min()) & (df['COL_1'] == 0), 'COL_2'] = -1
print(df)
# Output
COL_1  COL_2
2017-04-21    0.0   -1.0
2017-04-24    1.0    0.0
2017-04-25    0.0   -1.0