#how to trim a multi line string or a file

s=""" line one
\tline two\t
line three """

#line1 starts with a space, #2 starts and ends with a tab, #3 ends with a space.

s1=s.splitlines()
print s1
[' line one', '\tline two\t', 'line three ']

print [i.strip() for i in s1]
['line one', 'line two', 'line three']




#more details:

#we could also have used a forloop from the begining:
for line in s.splitlines():
    line=line.strip()
    process(line)

#we could also be reading a file line by line.. e.g. my_file=open(filename), or with open(filename) as myfile:
for line in my_file:
    line=line.strip()
    process(line)

#moot point: note splitlines() removed the newline characters, we can keep them by passing True:
#although split() will then remove them anyway..
s2=s.splitlines(True)
print s2
[' line one\n', '\tline two\t\n', 'line three ']

空格包括空格、制表符和CRLF。我们可以使用一个优雅的单行字符串函数翻译。

你好。翻译(不，不，不)

或者，如果你想彻底一点

import string
' hello  apple'.translate(None, string.whitespace)

如果你想去掉字符串开头和结尾的空白，你可以这样做:

some_string = "    Hello,    world!\n    "
new_string = some_string.strip()
# new_string is now "Hello,    world!"

这很像Qt的QString::()方法，因为它删除了开头和结尾的空白，而只保留内部空白。

但是，如果你想使用Qt的QString::simplified()方法，它不仅删除开头和结尾的空白，而且还将所有连续的内部空白“压缩”为一个空格字符，你可以使用.split()和" "的组合。像这样加入:

some_string = "\t    Hello,  \n\t  world!\n    "
new_string = " ".join(some_string.split())
# new_string is now "Hello, world!"

在最后一个示例中，每个内部空格序列都被替换为单个空格，同时仍然将字符串的开头和结尾的空白删除。

在Python中，trim方法被命名为strip:

str.strip()  # trim
str.lstrip()  # left trim
str.rstrip()  # right trim

在以不同程度的理解看了相当多的解决方案之后，我想知道如果字符串是逗号分隔的该怎么办……

这个问题

在尝试处理一个csv的联系信息时，我需要解决这个问题:删除无关的空格和一些垃圾，但保留后面的逗号和内部空格。使用一个包含联系人注释的字段，我想删除垃圾，留下好的东西。修剪掉所有的标点符号和杂物，我不想失去复合标记之间的空白，因为我不想以后重新构建。

正则表达式和模式:[\s_]+?\ W +

该模式以[\s_]+?出现在从1到无限时间的非单词字符之前，使用这个:\W+(相当于[^a-zA-Z0-9_])。具体来说，它可以找到大量的空白:空字符(\0)、制表符(\t)、换行符(\n)、前馈(\f)、回车符(\r)。

我认为这样做有两个好处:

它不会删除你可能想要放在一起的完整单词/标记之间的空白; Python内置的字符串方法strip()不处理字符串内部，只处理左右两端，默认的arg是空字符(参见下面的示例:文本中有几个换行符，strip()不会删除它们，而regex模式会删除它们)。文本。带(' t \ r \ n \ ')

这超出了OPs的问题，但我认为在文本数据中有很多情况下我们可能会遇到奇怪的、病态的实例，就像我所做的那样(一些转义字符最终出现在一些文本中)。此外，在类似列表的字符串中，我们不希望消除分隔符，除非分隔符分隔了两个空白字符或一些非单词字符，如'- '或'-，，，，'。

注意:不是在谈论CSV本身的分隔符。仅适用于CSV中数据类似列表的实例，即子字符串组成的c.s.字符串。

Full disclosure: I've only been manipulating text for about a month, and regex only the last two weeks, so I'm sure there are some nuances I'm missing. That said, for smaller collections of strings (mine are in a dataframe of 12,000 rows and 40 odd columns), as a final step after a pass for removal of extraneous characters, this works exceptionally well, especially if you introduce some additional whitespace where you want to separate text joined by a non-word character, but don't want to add whitespace where there was none before.

一个例子:

import re


text = "\"portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12,  2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, , , , \r, , \0, ff dd \n invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com s, \n i69rpofhfsp9t7c practice 20ignition - 20june \t\n .2134.pdf 2109                                                 \n\n\n\nklkjsdf\""

print(f"Here is the text as formatted:\n{text}\n")
print()
print("Trimming both the whitespaces and the non-word characters that follow them.")
print()
trim_ws_punctn = re.compile(r'[\s_]+?\W+')
clean_text = trim_ws_punctn.sub(' ', text)
print(clean_text)
print()
print("what about 'strip()'?")
print(f"Here is the text, formatted as is:\n{text}\n")
clean_text = text.strip(' \n\t\r')  # strip out whitespace?
print()
print(f"Here is the text, formatted as is:\n{clean_text}\n")

print()
print("Are 'text' and 'clean_text' unchanged?")
print(clean_text == text)

这个输出:

Here is the text as formatted:

"portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12,  2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, ,, , , ff dd 
 invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com s, 
 i69rpofhfsp9t7c practice 20ignition - 20june 
 .2134.pdf 2109                                                 



klkjsdf" 

using regex to trim both the whitespaces and the non-word characters that follow them.

"portfolio, derp, hello-world, hello-, world, founders, mentors, ffib, biff, 1, 12.18.02, 12, 2013, 9874890288, ff, series a, exit, general mailing, fr, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk,  jim.somedude@blahblah.com, dd invites,subscribed,, master, dd invites,subscribed, ff dd invites, subscribed, alumni spring 2012 deck: https: www.dropbox.com s, i69rpofhfsp9t7c practice 20ignition 20june 2134.pdf 2109 klkjsdf"

Very nice.
What about 'strip()'?

Here is the text, formatted as is:

"portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12,  2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, ,, , , ff dd 
 invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com s, 
 i69rpofhfsp9t7c practice 20ignition - 20june 
 .2134.pdf 2109                                                 



klkjsdf"


Here is the text, after stipping with 'strip':


"portfolio, derp, hello-world, hello-, -world, founders, mentors, :, ?, %, ,>, , ffib, biff, 1, 12.18.02, 12,  2013, 9874890288, .., ..., ...., , ff, series a, exit, general mailing, fr, , , ,, co founder, pitch_at_palace, ba, _slkdjfl_bf, sdf_jlk, )_(, jim.somedude@blahblah.com, ,dd invites,subscribed,, master, , , ,  dd invites,subscribed, ,, , , ff dd 
 invites, subscribed, , ,  , , alumni spring 2012 deck: https: www.dropbox.com s, 
 i69rpofhfsp9t7c practice 20ignition - 20june 
 .2134.pdf 2109                                                 



klkjsdf"
Are 'text' and 'clean_text' unchanged? 'True'

所以strip一次删除一个空白。所以在OPs的情况下，strip()是可以的。但如果事情变得更复杂，regex和类似的模式可能对更一般的设置有一定的价值。

看看它的实际应用

试着翻译

>>> import string
>>> print '\t\r\n  hello \r\n world \t\r\n'

  hello 
 world  
>>> tr = string.maketrans(string.whitespace, ' '*len(string.whitespace))
>>> '\t\r\n  hello \r\n world \t\r\n'.translate(tr)
'     hello    world    '
>>> '\t\r\n  hello \r\n world \t\r\n'.translate(tr).replace(' ', '')
'helloworld'