CODEWITHSUNDEEP
pythonioline-breaksreadlines
samwise
samwise

Reputation: 149

Read a file with line continuation characters in Python

I'm looking for a nice pythonic way of reading a file, and joining any lines which are logical continuations of the ones above, as indicated by a line continuation character. E.g. 

Here is a normal line.
This line continues over  \
two lines.
This line continues over\
three \
lines.

I've found one solution here: http://code.activestate.com/recipes/66064-reading-lines-with-continuation-characters, but it seems unwieldy. There is a nice solution from Daniel Wang in the comments using a generator:

def loglines(rawdata):
    lines = []
    for i in rawdata.splitlines():
        lines.append(i)
        if not i.endswith("\\"):
            yield "".join(lines)
            lines = []
    if len(lines)>0: yield "".join(lines)

This works fine, provided you can read the whole file at once. I wondered if there are any built-in functions which handle this, or whether anyone has any other suggestions.

Upvotes: 3

Views: 1851

Answers (1)

John La Rooy
John La Rooy

Reputation: 304137

with open("data.txt") as fin:
    for line in fin:
        line = line.rstrip('\n')
        while line.endswith('\\'):
            line = line[:-1] + next(fin).rstrip('\n')
        print line
        ...

You can also pull this out into a generator if you wish

def continuation_lines(fin):
    for line in fin:
        line = line.rstrip('\n')
        while line.endswith('\\'):
            line = line[:-1] + next(fin).rstrip('\n')
        yield line


with open("long.txt") as fin:
    for line in continuation_lines(fin):
        ...

Upvotes: 14

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