删除 pandas DataFrame 列中字符串条目的末尾

我有一个 pandas Dataframe，其中一列是文件列表

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   ....
....

我想删除文件扩展名.txt从每个条目filename。我该如何实现这个目标？

I tried:

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

但是当我随后查看列条目时df.head()， 什么也没有变。

如何做到这一点？

我想你可以使用str.replace http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.str.replace.html使用正则表达式.txt$' ( $ - 匹配字符串的结尾 https://docs.python.org/2/library/re.html):

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

EDIT:

rstrip如果字符串末尾包含条纹字符串的某些字符（在本例中），则可以删除更多字符., t, x):

Example:

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