CODEWITHSUNDEEP
pythonipythonpprint
David Wolever
David Wolever

Reputation: 154584

Is it possible to change IPython's pretty printer?

Is it possible to change the pretty printer that IPython uses?

I'd like to switch out the default pretty printer for pprint++, which I prefer for things like nested structures:

In [42]: {"foo": [{"bar": 42}, {"bar": 16}] * 3, "bar": [1,2,3,4,5]}
Out[42]: 
{'bar': [1, 2, 3, 4, 5],
 'foo': [{'bar': 42},
  {'bar': 16},
  {'bar': 42},
  {'bar': 16},
  {'bar': 42},
  {'bar': 16}]}

In [43]: pprintpp.pprint({"foo": [{"bar": 42}, {"bar": 16}] * 5, "bar": [1,2,3,4,5]})
{
    'bar': [1, 2, 3, 4, 5],
    'foo': [
        {'bar': 42},
        {'bar': 16},
        {'bar': 42},
        {'bar': 16},
        {'bar': 42},
        {'bar': 16},
        {'bar': 42},
        {'bar': 16},
        {'bar': 42},
        {'bar': 16},
    ],
}

Upvotes: 2

Views: 240

Answers (1)

Alyssa Haroldsen
Alyssa Haroldsen

Reputation: 3731

This can technically be done by monkey-patching the class IPython.lib.pretty.RepresentationPrinter used here in IPython.

This is how one might do it:

In [1]: o = {"foo": [{"bar": 42}, {"bar": 16}] * 3, "bar": [1,2,3,4,5]}

In [2]: o
Out[2]: 
{'bar': [1, 2, 3, 4, 5],
 'foo': [{'bar': 42},
  {'bar': 16},
  {'bar': 42},
  {'bar': 16},
  {'bar': 42},
  {'bar': 16}]}

In [3]: import IPython.lib.pretty

In [4]: import pprintpp

In [5]: class NewRepresentationPrinter:
            def __init__(self, stream, *args, **kwargs):
                self.stream = stream
            def pretty(self, obj):
                p = pprintpp.pformat(obj)
                self.stream.write(p.rstrip())
            def flush(self):
                pass


In [6]: IPython.lib.pretty.RepresentationPrinter = NewRepresentationPrinter

In [7]: o
Out[7]: 
{
    'bar': [1, 2, 3, 4, 5],
    'foo': [
        {'bar': 42},
        {'bar': 16},
        {'bar': 42},
        {'bar': 16},
        {'bar': 42},
        {'bar': 16},
    ],
}

This is a bad idea for a multitude of reasons, but should technically work for now. Currently it doesn't seem there's an official, supported way to override all pretty-printing in IPython, at least simply.

(note: the .rstrip() is needed because IPython doesn't expect a trailing newline on the result)

Upvotes: 6

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