get only additions in difflib.unified_diff

[metulburr]

Im using difflib to mimic git diff between two files in python. It works as expected and as git diff does it. However i am wondering if you can only get the additions of the different files?

What defines additional VS removals?

Im using it in this manner:

if args['diff']:
    old = open(args['output'])
    new = output_str
    for line in difflib.unified_diff(old.readlines(), new.splitlines(True), fromfile=old.name,           tofile='current', lineterm='\n'):
        print(line)
    old.close()

an example snippet output would be

Output:
-9911 Church Creek Rd Lindley, NY 14858

-Thursday May 04, 2017 - Saturday May 06, 2017 Time: 7:00AM - 4:00PM

-Crafts, tools, kitchen items, yarn, power washer, ab roller, fishing poles too much to list.

+638 River Rd Lindley, NY 14858

+Saturday May 06, 2017 - Saturday May 13, 2017 Time: 9:00AM

+Everything must go!!!!!

is what i current get, when i only want to see

+638 River Rd Lindley, NY 14858

+Saturday May 06, 2017 - Saturday May 13, 2017 Time: 9:00AM

+Everything must go!!!!!

I dont see any additional arguments to give such restrictions

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Help on function unified_diff in module difflib:

unified_diff(a, b, fromfile='', tofile='', fromfiledate='', tofiledate='', n=3, lineterm='\n')
    Compare two sequences of lines; generate the delta as a unified diff.
    
    Unified diffs are a compact way of showing line changes and a few
    lines of context.  The number of context lines is set by 'n' which
    defaults to three.
    
    By default, the diff control lines (those with ---, +++, or @@) are
    created with a trailing newline.  This is helpful so that inputs
    created from file.readlines() result in diffs that are suitable for
    file.writelines() since both the inputs and outputs have trailing
    newlines.
    
    For inputs that do not have trailing newlines, set the lineterm
    argument to "" so that the output will be uniformly newline free.
    
    The unidiff format normally has a header for filenames and modification
    times.  Any or all of these may be specified using strings for
    'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.
    The modification times are normally expressed in the ISO 8601 format.
    
    Example:
    
    >>> for line in unified_diff('one two three four'.split(),
    ...             'zero one tree four'.split(), 'Original', 'Current',
    ...             '2005-01-26 23:30:50', '2010-04-02 10:20:52',
    ...             lineterm=''):
    ...     print line                  # doctest: +NORMALIZE_WHITESPACE
    --- Original        2005-01-26 23:30:50
    +++ Current         2010-04-02 10:20:52
    @@ -1,4 +1,4 @@
    +zero
     one
    -two
    -three
    +tree
     four

Is this possible with just difflib or would it require string parsing to do?

[ichabod801]

I notice you're using splitlines, which removes trailing \n's. There's this note in the docs:

For inputs that do not have trailing newlines, set the lineterm argument to "" so that the output will be uniformly newline free.

Could that have something to do with it?

[metulburr]

im not worried about the newlines, just obtaining only additions VS deletions.

[volcano63]

im not worried about the newlines, just obtaining only additions VS deletions.

I don't think you have such an option - just filter out every line that doesn't start with +[space]