Disabling sorting mechanism in pprint output

Python 3.8 or newer:

Use sort_dicts=False:

pprint.pprint(data, sort_dicts=False)

Python 3.7 or older:

You can monkey patch the pprint module.

import pprint

pprint.pprint({"def":2,"ghi":3,"abc":1,})
pprint._sorted = lambda x:x
# Or, for Python 3.7:
# pprint.sorted = lambda x, key=None: x
pprint.pprint({"def":2,"ghi":3, "abc":1})

Since the 2nd output is essentiallly randomly sorted, your output may be different from mine:

{'abc': 1, 'def': 2, 'ghi': 3}
{'abc': 1, 'ghi': 3, 'def': 2}

---

Another version that is more complex, but easier to use:

import pprint
import contextlib

@contextlib.contextmanager
def pprint_nosort():
    # Note: the pprint implementation changed somewhere
    # between 2.7.12 and 3.7.0. This is the danger of
    # monkeypatching!
    try:
        # Old pprint
        orig,pprint._sorted = pprint._sorted, lambda x:x
    except AttributeError:
        # New pprint
        import builtins
        orig,pprint.sorted = None, lambda x, key=None:x

    try:
        yield
    finally:
        if orig:
            pprint._sorted = orig
        else:
            del pprint.sorted

# For times when you don't want sorted output
with pprint_nosort():
    pprint.pprint({"def":2,"ghi":3, "abc":1})

# For times when you do want sorted output
pprint.pprint({"def":2,"ghi":3, "abc":1})

As of Python 3.8, you can finally disable this using sort_dicts=False. Note that dictionaries are insertion-ordered since Python 3.7 (and in practice, even since 3.6).

import pprint

data = {'not': 'sorted', 'awesome': 'dict', 'z': 3, 'y': 2, 'x': 1}
pprint.pprint(data, sort_dicts=False)
# prints {'not': 'sorted', 'awesome': 'dict', 'z': 3, 'y': 2, 'x': 1}

Alternatively, create a pretty printer object:

pp = pprint.PrettyPrinter(sort_dicts=False)
pp.pprint(data)

This does not affect sets (which are still sorted), but then sets do not have insertion-ordering guarantees.