删除pandas DataFrame列中的字符串条目的结尾 [英] Remove ends of string entries in pandas DataFrame column

问题描述

我有一个熊猫数据框，其中有一列是文件列表

I have a pandas Dataframe with one column a list of files

import pandas as pd
df = pd.read_csv('fname.csv')

df.head()

filename    A    B    C
fn1.txt   2    4    5
fn2.txt   1    2    1
fn3.txt   ....
....

我想从文件 中的每个条目中删除文件扩展名 .txt 。我该怎么做？

I would like to delete the file extension .txt from each entry in filename. How do I accomplish this?

我尝试过：

df['filename'] = df['filename'].map(lambda x: str(x)[:-4])

但是当我之后用 df.head（）查看列条目时，没有任何变化。

but when I look at the column entries afterwards with df.head(), nothing has changed.

这是怎么做的？

推荐答案

我认为您可以使用 str.replace 和正则表达式 .txt $ '（ $ -匹配字符串的结尾）：

I think you can use str.replace with regex .txt$' ( $ - matches the end of the string):

import pandas as pd

df = pd.DataFrame({'A': {0: 2, 1: 1}, 
                   'C': {0: 5, 1: 1}, 
                   'B': {0: 4, 1: 2}, 
                   'filename': {0: "txt.txt", 1: "x.txt"}}, 
                columns=['filename','A','B', 'C'])

print df
  filename  A  B  C
0  txt.txt  2  4  5
1    x.txt  1  2  1

df['filename'] = df['filename'].str.replace(r'.txt$', '')
print df
  filename  A  B  C
0      txt  2  4  5
1        x  1  2  1

df['filename'] = df['filename'].map(lambda x: str(x)[:-4])
print df
  filename  A  B  C
0      txt  2  4  5
1        x  1  2  1

df['filename'] = df['filename'].str[:-4]
print df
  filename  A  B  C
0      txt  2  4  5
1        x  1  2  1

编辑：

rstrip 可以删除更多字符，如果字符串的末尾包含带条纹的字符串的某些字符（在本例中为。， t ， x ）：

rstrip can remove more characters, if the end of strings contains some characters of striped string (in this case ., t, x):

示例：

print df
  filename  A  B  C
0  txt.txt  2  4  5
1    x.txt  1  2  1

df['filename'] = df['filename'].str.rstrip('.txt')

print df
  filename  A  B  C
0           2  4  5
1           1  2  1

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