提取具有特殊字符的正则表达式

Question

我想基于另一列 ID 在 pandas 数据框 df 中创建一列。对于包含字符串SAT 的ID，我想提取由特殊字符“-”连接的浮点数，并将提取的数据放入一个名为new_col 的新列中。如果ID 不包含SAT 字符串，则保留为NaN。

df如下：

    Date        ID                   Time
0   2007-01-10  SAT 1 HHSP           900
1   2007-01-10  DOUBLE 7 HHSP        900
2   2007-01-10  SAT GF-06-5CSBG.431  1000
3   2007-01-10  MA HYDRO HHSP        900
4   2007-01-10  2.233 HHSP           900
5   2007-01-10  SAT L2-15-3CSB1.252  1000
6   2007-01-10  SECTION 6 HHSP       900

预期输出：

    Date        ID                   Time     new_col
0   2007-01-10  SAT 1 HHSP           900      NaN
1   2007-01-10  DOUBLE 7 HHSP        900      NaN
2   2007-01-10  SAT GF-06-5CSBG.431  1000     06-5
3   2007-01-10  MA HYDRO HHSP        900      NaN
4   2007-01-10  2.233 HHSP           900      NaN
5   2007-01-10  SAT L2-15-3 CSB1.252  1000    15-3  * In this case 15-3 instead of 2-15 is extracted because L2 is not completely floats.
6   2007-01-10  SECTION 6 HHSP       900      NaN

Answer 1

将Series.str.extract 与由- 连接的数字和前面的- 一起使用，并且仅用于SAT 由Series.str.contains 过滤的值：

m = df['ID'].str.contains('SAT')
df['new_col'] = df.loc[m, 'ID'].str.extract('[-\s+](\d+\-\d+)')
print (df)
         Date                   ID  Time new_col
0  2007-01-10           SAT 1 HHSP   900     NaN
1  2007-01-10        DOUBLE 7 HHSP   900     NaN
2  2007-01-10  SAT GF-06-5CSBG.431  1000    06-5
3  2007-01-10        MA HYDRO HHSP   900     NaN
4  2007-01-10           2.233 HHSP   900     NaN
5  2007-01-10  SAT L2-15-3CSB1.252  1000    15-3
6  2007-01-10       SECTION 6 HHSP   900     NaN

如果值SAT 可以在列中开始使用：

df['new_col'] = df['ID'].str.extract('^SAT.*[-\s+](\d+\-\d+)', expand=False)