python pandas部分字符串匹配

Question

我创建了一个数据帧df,其中我有一个包含以下值的列:

category
20150115_Holiday_HK_Misc
20150115_Holiday_SG_Misc
20140116_DE_ProductFocus
20140116_UK_ProductFocus

我想创建3个新列

category                  |           A              |  B  |       C     
20150115_Holiday_HK_Misc     20150115_Holiday_Misc     HK    Holiday_Misc 
20150115_Holiday_SG_Misc     20150115_Holiday_Misc     SG    Holiday_Misc
20140116_DE_ProductFocus     20140116_ProductFocus     DE    ProductFocus
20140116_UK_ProductFocus     20140116_ProductFocus     UK    ProductFocus

在A栏中,我想取出"_HK" - 我想我需要手动编码,但这很好,我有所有国家代码的列表

在B栏中,就是那个国家代码

C列是A列,没有开头的日期

我正在尝试这样的事情,但没有走得太远.

 df['B'] = np.where([df['category'].str.contains("HK")==True], 'HK', 'Not Specified')

谢谢

Answer 1

你可以使用Series.str.extract()方法:

# remove two characters (Country Code) surrounded by '_'
df['A'] = df.category.str.replace(r'_\w{2}_', '_')
# extract two characters (Country Code) surrounded by '_' 
df['B'] = df.category.str.extract(r'_(\w{2})_', expand=False)
df['C'] = df.A.str.extract(r'\d+_(.*)', expand=False)

结果:

In [148]: df
Out[148]:
                   category                      A   B             C
0  20150115_Holiday_HK_Misc  20150115_Holiday_Misc  HK  Holiday_Misc
1  20150115_Holiday_SG_Misc  20150115_Holiday_Misc  SG  Holiday_Misc
2  20140116_DE_ProductFocus  20140116_ProductFocus  DE  ProductFocus
3  20140116_UK_ProductFocus  20140116_ProductFocus  UK  ProductFocus