python - 根据条件创建虚拟 DataFrame

Question

我尝试根据具有多个条件的 DataFrame df 创建一个虚拟 DataFrame df_dummy。

• 如果值 > 0 --> 1
• 如果值 < 0 --> 0
• 否则 (0, NaN) --> 0

df:
            ID1     ID2     ID3
Date            
2022-01-01  -1.0    -0.1    0.0
2022-01-02  0.0     1.2     0.7
2022-01-03  NaN     2.0     1.0
2022-01-04  -0.8    0.0     0.0
2022-01-05  1.1     NaN     -0.5

df_dummy:
            ID1     ID2     ID3
Date            
2022-01-01  0       0       NaN
2022-01-02  NaN     1       1
2022-01-03  NaN     1       1
2022-01-04  NAN     NaN     NaN
2022-01-05  1       NaN     0

我试过为假人定义一个信号:

def signal(x):
    if(x>0): 
        return 1
    elif(x<0):
        return 0
    else:
        return np.nan
df_dummy = df[:].apply(lambda x: signal, axis=1)

data_signal = df[:].apply(lambda x: 1 if x>0 -1 if x<0 else np.nan, axis=1)

有没有一种直观的方法可以为 df_dummy 创建这样的条件？

非常感谢!

Answer 1

你可以使用np.select:

# np.select returns a numpy array
# so we copy data to reserve index/columns
df_dummy = df.copy()
df_dummy[:] = np.select((df > 0, df < 0), (1, 0), np.nan)

还有:

df_dummy = pd.DataFrame(np.select((df > 0, df < 0), (1, 0), np.nan),
                        index=df.index, columns=df.columns)

输出:

            ID1  ID2  ID3
Date                     
2022-01-01  0.0  0.0  NaN
2022-01-02  NaN  1.0  1.0
2022-01-03  NaN  1.0  1.0
2022-01-04  0.0  NaN  NaN
2022-01-05  1.0  NaN  0.0