无法使用正则表达式为中的值集找到第一个出现的子字符串

Question

我有一个如下所示的数据帧，我只需要在一组值的字符串中找到第一个匹配项。你知道吗

我无法将“find”函数与regex和dictionary一起使用。如果我使用“findall”函数，它当然会查找所有不需要的事件。你知道吗

Text

51000/1-PLASTIC 150 Prange
51034/2-RUBBER KL 100 AA
51556/3-PAPER BD+CM 1 BOXT2
52345/1-FLOW IJ 10place 500 plastic
54975/1-DIVIDER PQR 100 BC
54975/1-SCALE DEF 555 AB Apple 
54975/1-PLASTIC ABC 4.6 BB plastic  

代码：

import re

L = ['PLASTIC','RUBBER','PAPER','FLOW']
pat = '|'.join(r"\b{}\b".format(x) for x in L)

df['Result'] = df['Text'].str.find(pat, flags=re.I).str.join(' ')
print(df)

df = df.replace(r'^\s*$', np.nan, regex=True)
df = df.replace(np.nan, "Not known", regex=True)
#df['Result'] = df['Result'].str.lower()

预期结果：

Text                                                   Result

51000/1-PLASTIC 150 Prange                            Plastic
51034/2-RUBBER KL 100 AA                              Rubber
51556/3-PAPER BD+CM 1 BOXT2                           Paper
52345/1-FLOW IJ 10place 500 plastic                   Flow
54975/1-DIVIDER PQR 100 BC                            Not known
54975/1-SCALE DEF 555 AB Apple                        Not KNown 
54975/1-PLASTIC ABC 4.6 BB plastic                    Plastic

错误：

TypeError: find() got an unexpected keyword argument 'flags'

Answer 1

使用^{}而不是find，通过索引str[0]来选择返回findall的列表的第一个值：

import re

L = ['PLASTIC','RUBBER','PAPER','FLOW']
pat = '|'.join(r"\b{}\b".format(x) for x in L)

df['Result'] = df['Text'].str.findall(pat, flags=re.I).str[0]

或使用^{}：

df['Result'] = df['Text'].str.extract('(' + pat + ')', flags=re.I)

---

然后将缺少的值转换为Not known：

df['Result'] = df['Result'].fillna("Not known")

如有必要，最后使用^{}：

df['Result'] = df['Result'].str.capitalize()
print (df)
                                   Text     Result
0            51000/1-PLASTIC 150 Prange    Plastic
1              51034/2-RUBBER KL 100 AA     Rubber
2           51556/3-PAPER BD+CM 1 BOXT2      Paper
3   52345/1-FLOW IJ 10place 500 plastic       Flow
4            54975/1-DIVIDER PQR 100 BC  Not known
5        54975/1-SCALE DEF 555 AB Apple  Not known
6  54975/1-PLASTIC ABC 4.6 BB plastic      Plastic