Python 删除 pandas DataFrame 列中字符串条目的结尾
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Remove ends of string entries in pandas DataFrame column
提问by ShanZhengYang
I have a pandas Dataframe with one column a list of files
我有一个熊猫数据框，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 ....
....
I would like to delete the file extension .txtfrom each entry in filename. How do I accomplish this?
我想.txt从filename. 我该如何实现？
I tried:
我试过：
df['filename'] = df['filename'].map(lambda x: str(x)[:-4])
but when I look at the column entries afterwards with df.head(), nothing has changed.
但是当我之后查看列条目时df.head()，没有任何变化。
How does one do this?
如何做到这一点？
回答by jezrael
I think you can use str.replacewith regex .txt$'( $- matches the end of the string):
我认为您可以使用str.replace正则表达式.txt$'（$-匹配字符串的结尾）：
import pandas as pd
df = pd.DataFrame({'A': {0: 2, 1: 1},
'C': {0: 5, 1: 1},
'B': {0: 4, 1: 2},
'filename': {0: "txt.txt", 1: "x.txt"}},
columns=['filename','A','B', 'C'])
print df
filename A B C
0 txt.txt 2 4 5
1 x.txt 1 2 1
df['filename'] = df['filename'].str.replace(r'.txt$', '')
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:
编辑：
rstripcan remove more characters, if the end of strings contains some characters of striped string (in this case ., t, x):
rstrip可以删除更多的字符，如果字符串的末尾包含一些条纹字符串的字符（在这种情况下为., t, x）：
Example:
例子：
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
回答by EdChum
You can use str.rstripto remove the endings:
您可以使用str.rstrip删除结尾：
df['filename'] = df['filename'].str.rstrip('.txt')
should work
应该管用
回答by Pawe? Kordek
You may want:
你可能想要：
df['filename'] = df.apply(lambda x: x['filename'][:-4], axis = 1)
df['filename'] = df.apply(lambda x: x['filename'][:-4], axis = 1)
回答by Blue Moon
use list comprehension
使用列表理解
df['filename'] = [x[:-4] for x in df['filename']]
