Nested-Diff.py

Recursive diff and patch for nested structures.

Main features

Machine readable diff structure.
Human friendly diff visualization, collapsible html diffs.
All ops (added/removed/changed/unchanged) are optional and may be disabled.
Any data types support may be added by external handlers.

See Live Demo!

Install

pip install nested_diff

For extra formats support (YAML, TOML) in cli tools, use

pip install nested_diff[cli]

Command line tools

$ cat a.json b.json
[0, [1],    3]
[0, [1, 2], 3]

$ nested_diff a.json b.json
  [1]
+   [1]
+     2

nested_diff a.json b.json --ofmt json > patch.json
nested_patch a.json patch.json

Library usage

>>> from nested_diff import diff, patch
>>> from nested_diff.formatters import TextFormatter
>>>
>>> a = {'one': 1, 'two': 2, 'three': 3}
>>> b = {'one': 1, 'two': 42}
>>>
>>>
>>> full_diff = diff(a, b)
>>> full_diff
{'D': {'three': {'R': 3}, 'two': {'N': 42, 'O': 2}, 'one': {'U': 1}}}
>>>
>>> short_diff = diff(a, b, O=False, U=False)  # omit old and unchanged items
>>> short_diff
{'D': {'three': {'R': 3}, 'two': {'N': 42}}}
>>>
>>>
>>> a = patch(a, short_diff)
>>> assert a == b
>>>
>>>
>>> human_readable = TextFormatter().format(full_diff)
>>> print(human_readable)
  {'one'}
    1
- {'three'}
-   3
  {'two'}
-   2
+   42
<BLANKLINE>
>>>

HTML and ANSI colored terminal formatters also available out of the box.
See Live Demo,
HOWTO and
nested_diff.formatters.

Diff structure

Diff is a dict and may contain status keys:

A stands for ‘added’, it’s value - added item.
D means ‘different’ and contains subdiff.
N is a new value for changed item.
O is a changed item’s old value.
R key used for removed item.
U represent unchanged item.

and auxiliary keys:

C comment; optional, value - arbitrary string.
E extension ID (optional).
I index for sequence item, used only when prior item was omitted.

Diff metadata alternates with actual data; simple types specified as is, dicts,
lists and tuples contain subdiffs for their items with native for such types
addressing: indexes for lists and tuples, keys for dictionaries. Any status
key, except D may be omitted during diff computation. E key is used with
D when entity unable to contain diff by itself (set, frozenset for example);
D contain a list of subdiffs in this case.

Annotated example

a:  {"one": [5,7]}
b:  {"one": [5], "two": 2}
opts: U=False  # omit unchanged items
diff:
{"D": {"one": {"D": [{"I": 1, "R": 7}]}, "two": {"A": 2}}}
| |   |  |    | |   || |   |   |   |       |    | |   |
| |   |  |    | |   || |   |   |   |       |    | |   +- with value 2
| |   |  |    | |   || |   |   |   |       |    | +- key 'two' was added
| |   |  |    | |   || |   |   |   |       |    +- subdiff for it
| |   |  |    | |   || |   |   |   |       +- another key from top-level
| |   |  |    | |   || |   |   |   +- what it was (item's value: 7)
| |   |  |    | |   || |   |   +- what happened to item (removed)
| |   |  |    | |   || |   +- list item's actual index
| |   |  |    | |   || +- prior item was omitted
| |   |  |    | |   |+- subdiff for list item
| |   |  |    | |   +- it's value - list
| |   |  |    | +- it is deeply changed
| |   |  |    +- subdiff for key 'one'
| |   |  +- it has key 'one'
| |   +- top-level thing is a dict
| +- changes somewhere deeply inside
+- diff is always a dict

License

Licensed under the terms of the Apache License, Version 2.0.