#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 ']

这将删除字符串开头和结尾的所有空格和换行符:

>>> s = "  \n\t  \n   some \n text \n     "
>>> re.sub("^\s+|\s+$", "", s)
>>> "some \n text"

一般来说，我使用的方法如下:

>>> myStr = "Hi\n Stack Over \r flow!"
>>> charList = [u"\u005Cn",u"\u005Cr",u"\u005Ct"]
>>> import re
>>> for i in charList:
        myStr = re.sub(i, r"", myStr)

>>> myStr
'Hi Stack Over  flow'

注意:这只用于删除“\n”，“\r”和“\t”。它不会删除额外的空格。

你也可以使用非常简单的基本函数:str.replace()，用于空格和制表符:

>>> whitespaces = "   abcd ef gh ijkl       "
>>> tabs = "        abcde       fgh        ijkl"

>>> print whitespaces.replace(" ", "")
abcdefghijkl
>>> print tabs.replace(" ", "")
abcdefghijkl

简单易行。

前导空格和尾随空格:

s = '   foo    \t   '
print s.strip() # prints "foo"

否则，正则表达式工作:

import re
pat = re.compile(r'\s+')
s = '  \t  foo   \t   bar \t  '
print pat.sub('', s) # prints "foobar"

(re.sub(' +'， ' '，(my_str。取代(' \ n ',' ')))). 带()

这将删除所有不需要的空格和换行符。希望这对你有所帮助

import re
my_str = '   a     b \n c   '
formatted_str = (re.sub(' +', ' ',(my_str.replace('\n',' ')))).strip()

这将导致:

'a b \n c'将被更改为'a bc '