Pandas：统计单词的出现次数（来自另一个数据帧），并输出计数和匹配的单词

Question

我有一个数据框（df），其中有一列包含句子。我有第二个数据帧（df2），其中有一列包含单词。在df中的每一行，我想计算一个来自df2的单词在句子中出现的次数，如果确实出现，则将计数输出到一个新列中，并将匹配的单词输出到一个新列中

我已经计算出了如何进行计数，但是我无法计算出如何输出匹配的单词-请参阅df_desiredoutput数据帧了解我想要的内容。提前谢谢

下面是一些伪代码

import pandas as pd
import re

df = pd.DataFrame({'sentence': ['Hello how are you', 'It is nice outside today', 'I need to water the plants', 'I need to cook dinner', 'See you tommorow']})
print(df)

df2 = pd.DataFrame({'words': ['hello', 'you', 'plants', 'need', 'tommorow']})
print(df2)

df["count"] = df["sentence"].str.count('|'.join(df2['words']), re.I)
print(df)

df_desiredoutput = pd.DataFrame({'sentence': ['Hello, how are you?', 'It is nice outside today', 'I need to water the plants', 'I need to cook dinner', 'See you tommorow'],
                          'count': ['2', '0', '2', '1', '2'],
                          'match': ['hello; you', '', 'need; plants', 'need', 'you; tomorrow']})
print(df_desiredoutput)

Answer 1

将^{}与^{}一起使用：

pat = '|'.join(df2['words'])
df["count"] = df["sentence"].str.count(pat, re.I)
df["match"] = df["sentence"].str.findall(pat, re.I).str.join('; ')
print(df)
                     sentence  count          match
0           Hello how are you      2     Hello; you
1    It is nice outside today      0               
2  I need to water the plants      2   need; plants
3       I need to cook dinner      1           need
4            See you tommorow      2  you; tommorow