Python 从B列获取A列中找到的字符串计数，并在新列中返回值

我试图得到熊猫中第二列中一列内容的计数。我想把频率计数放在一个叫做频率的新列中

我想在名为[Frequency]的新列中的[Description]列中找到我的[Keyword]列中的字符串的次数

所需输出

[keyword]           [Description]          [Frequency]
car                 car dog car car             3
car                 car dog dog dog             1
new car             old car car dog             0

   keyword       Description  frequency
0      car   car dog car car          3
1      car   car dog dog dog          1
2  new car   old car car dog          0

我尝试过的代码

我尝试了以下代码，但有两个问题。（频率计数不准确，格式完全错误）

---

如果精确匹配不重要，请使用

count

，这意味着如果

carito

在描述中匹配

car

。如果需要避免，请使用

@Dani Mesejo

回答

df['new'] = df.apply(lambda x: x['Description'].count(x['keyword']), axis=1)
print (df)
   keyword      Description  Frequency  new
0      car  car dog car car          3    3
1      car  car dog dog dog          1    1
2  new car  old car car dog          0    0

---

如果要精确匹配单词，请使用此选项：

df['frequency'] = [len(re.findall(rf'\b{k}\b', d)) for k, d in zip(df['keyword'], df['Description'])]
print(df)

输出

[keyword]           [Description]          [Frequency]
car                 car dog car car             3
car                 car dog dog dog             1
new car             old car car dog             0

   keyword       Description  frequency
0      car   car dog car car          3
1      car   car dog dog dog          1
2  new car   old car car dog          0

@jezrael建议的更好的替代方案是：

df['frequency'] = [len(re.findall(rf'\b{k}\b', d)) for k, d in df[['Description', 'keyword']].to_numpy()]