python - 在 Pandas 的整个列中计算字符串的出现次数

Question

考虑以下数据框:

import pandas as pd
df = pd.DataFrame(["What is the answer", 
                   "the answer isn't here, but the answer is 42" , 
                   "dogs are nice", 
                   "How are you"], columns=['words'])
df
                                         words
0                           What is the answer
1  the answer isn't here, but the answer is 42
2                                dogs are nice
3                                  How are you

我想统计某个字符串出现的次数，它可能在每个索引中重复几次。

例如，我想统计答案出现的次数。 我试过:

df.words.str.contains(r'the answer').count()

我希望得到一个解决方案，但输出是 4。 我不明白为什么。 答案出现了 3 次。

What is **the answer**
**the answer** isn't here, but **the answer** is 42

注意:搜索字符串可能在行中出现多次

Answer 1

你需要str.count

In [5285]: df.words.str.count("the answer").sum()
Out[5285]: 3

In [5286]: df.words.str.count("the answer")
Out[5286]:
0    1
1    2
2    0
3    0
Name: words, dtype: int64