How can I remove the first line of a multi-line string? (SOLVED)
Roy Smith
roy at panix.com
Mon Sep 2 13:07:11 EDT 2013
In article <mailman.500.1378139057.19984.python-list at python.org>,
Anthony Papillion <papillion at gmail.com> wrote:
> On 09/02/2013 11:12 AM, Chris âKwpolskaâ Warrick wrote:
> > On Mon, Sep 2, 2013 at 6:06 PM, Anthony Papillion <papillion at gmail.com>
> > wrote:
> >> Hello Everyone,
> >>
> >> I have a multi-line string and I need to remove the very first line from
> >> it. How can I do that? I looked at StringIO but I can't seem to figure
> >> out how to properly use it to remove the first line. Basically, I want
> >> to toss the first line but keep everything else. Can anyone put me on
> >> the right path? I know it is probably easy but I'm still learning Python
> >> and don't have all the string functions down yet.
> >>
> >> Thanks,
> >> Anthony
> >> --
> >> http://mail.python.org/mailman/listinfo/python-list
> >
> > Use split() and join() methods of strings, along with slicing. Like this:
> >
> > fullstring = """foo
> > bar
> > baz"""
> >
> > sansfirstline = '\n'.join(fullstring.split('\n')[1:])
> >
> > The last line does this:
> > 1. fullstring.split('\n') turns it into a list of ['foo', 'bar', 'baz']
> > 2. the [1:] slice removes the first element, making it ['bar', 'baz']
> > 3. Finally, '\n'.join() turns the list into a string separated by
> > newlines ("""bar
> > baz""")
>
> This, of course, worked like a charm. I really need to study the string
> methods. In the work I'm doing they are going to come in very handy.
> Thank you, Chris!
Let me toss out a couple of other possibilities. Not necessarily
better, but if you're learning about strings, you might as well learn
some other ways to do it:
s = """foo
bar
baz"""
print "using index..."
i = s.index('\n')
print s[i+1:]
print "using regex..."
import re
print re.sub(r'^[^\n]*\n', '', s)
I'll admit, the split/slice/join solution is probably the easiest to
implement (and to understand when you're reading the code). But, it
copies all the data twice; once when split() runs, and again when join()
runs. Both the index and regex solutions should only do a single copy.
For huge strings, this might matter. For a three-liner as in your
example, it doesn't make any difference.
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