= Python DiffLib =

'''`difflib`''' is a module for producing file deltas.

<<TableOfContents>>

----



== Usage ==

Consider an 'old' file like:

{{{
foo
bar


baz
1
2
3
}}}

And a 'new' file like:

{{{
foo
bar
baz
1
5
3
}}}

----



=== Context Diff ===

Use '''`context_diff`''' to create a delta in context diff format.

To create a file like:

{{{
*** a.txt
--- b.txt
***************
*** 1,9 ****
  foo
  bar
- 
- 
  baz
  1
! 2
  3
  
--- 1,7 ----
  foo
  bar
  baz
  1
! 5
  3

}}}

Try:

{{{
import difflib

with open('a.txt', 'r') as f:
    old = f.readlines()
with open('b.txt', 'r') as f:
    new = f.readlines()

d = difflib.context_diff(old, new, fromdesc='a.txt', todesc='b.txt')

with open('diff.txt', "w") as f:
    f.writelines(d)
}}}

----



=== Differ ===

Use '''`ndiff`''' to create a delta in differ style.

Try create a file like:

{{{
  foo
  bar
- 
- 
  baz
  1
- 2
+ 5
  3
}}}

Try:

{{{
import difflib

with open('a.txt', 'r') as f:
    old = f.readlines()
with open('b.txt', 'r') as f:
    new = f.readlines()

d = difflib.ndiff(old, new)

with open('diff.txt', "w") as f:
    f.writelines(d)
}}}

----



=== Unified Diff ===

Use '''`unified_diff`''' to create a delta in unified diff format.

To create a file like:

{{{
--- a.txt
+++ b.txt
@@ -1,9 +1,7 @@
 foo
 bar
-
-
 baz
 1
-2
+5
 3
}}}

Try:

{{{
import difflib

with open('a.txt', 'r') as f:
    old = f.readlines()
with open('b.txt', 'r') as f:
    new = f.readlines()

d = difflib.unified_diff(old, new, fromdesc='a.txt', todesc='b.txt')

with open('diff.txt', "w") as f:
    f.writelines(d)
}}}

----



=== HTML Table ===

To create a stylized HTML table with line-by-line comparisons, use the '''`HtmlDiff`''' class.

{{{
import difflib

with open('a.txt', 'r') as f:
    old = f.readlines()
with open('b.txt', 'r') as f:
    new = f.readlines()

d = difflib.HtmlDiff(wrapcolumn=80).make_file(old, new, fromdesc='a.txt', todesc='b.txt')

with open('diff.html', "w") as f:
    f.write(d)
}}}

----



== Functions ==

=== Diff_Bytes ===

=== Get_Close_Matches ===

=== Is_Character_Junk ===

=== Is_Line_Junk ===

=== Restore ===

----



== Classes ==

=== Differ ===

=== SequenceMatcher ===

----



== See also ==

[[https://docs.python.org/3/library/difflib.html|Python difflib module documentation]]

[[https://pymotw.com/3/difflib/|Python Module of the Day article for difflib]]



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CategoryRicottone