python-从字符串的结尾和开头删除空行

Question

I want to remove all empty lines from the beginning and the end of a string.

So the following:

s = """


        some identation here

lorem ipsum

"""

Would become:

s = """        some identation here

lorem ipsum"""

I don't like my solutions. I want something as simple and short as possible.

Is there something built-in in python3? What are your suggestions?

Answer 1

You'll have to use a custom solution. Split the lines by newlines, and remove empty lines from the start and end:

def strip_empty_lines(s):
    lines = s.splitlines()
    while lines and not lines[0].strip():
        lines.pop(0)
    while lines and not lines[-1].strip():
        lines.pop()
    return '\n'.join(lines)

This handles the case where the 'empty' lines still contain spaces or tabs, apart from the \\n line separators:

>>> strip_empty_lines('''\
... 
... 
... 
... 
...         some indentation here
... 
... lorem ipsum
... 
... 
... ''')
'        some indentation here\n\nlorem ipsum'
>>> strip_empty_lines('''\
... \t  \t
...     \n
...         some indentation here
... 
... lorem ipsum
... 
... ''')
'        some indentation here\n\nlorem ipsum'

If there is no other whitespace than newlines, then a simple s.strip('\\n') will do:

>>> '''\
... 
... 
... 
...         some indentation here
... 
... lorum ipsum
... 
... '''.strip('\n')
'        some indentation here\n\nlorum ipsum'

Answer 2

s = """




  some indentation here

lorem ipsum


""" 

x = s.strip("\n")
print(x)

yields

      some indentation here

lorem ipsum