从数据帧中查找字符串中的子字符串索引

Question

我有一个包含两列（和许多行）的数据帧，一列是完整序列，另一列是contains a sub sequence.

我想找到完整序列中子序列开始位置的索引，并将其添加为另一列：

我试过这个：

df["start"] = df.sequence.index(df.sub_sequence)

但这返回：TypeError: 'RangeIndex' object is not callable

我做错了什么

以下是df和我希望结束的df：

示例数据帧：

import pandas as pd 

data = {"sequence": ["abcde","fghij","klmno"], "sub_sequence": ["cde", "gh", "no"]}    
df = pd.DataFrame (data, columns = ['sequence','sub_sequence'])

  sequence sub_sequence
0    abcde          cde
1    fghij           gh
2    klmno           no

---

预期结果：

data2 = {"sequence": ["abcde","fghij","klmno"], "sub_sequence": ["cde", "gh", "no"], "start": [2,1,3]}
df2 = pd.DataFrame (data2, columns = ['sequence','sub_sequence','start'])

  sequence sub_sequence  start
0    abcde          cde      2
1    fghij           gh      1
2    klmno           no      3

Answer 1

在列表理解中使用^{}和^{}：

df['start'] = [seq.index(sub) for seq, sub in zip(df['sequence'], df['sub_sequence'])]

或者沿着{}+{a2}使用{a3}：

df['start'] = df[['sequence', 'sub_sequence']].apply(lambda s: str.index(*s), axis=1)

结果:

  sequence sub_sequence  start
0    abcde          cde      2
1    fghij           gh      1
2    klmno           no      3