REF: register custom DisplayFormatter for table schema (#16198)

* register custom DisplayFormatter for table schema

instead of using `_ipython_display_` for custom mime-types

* remove unused UnserializableWarning

* PEP8 fixes

Author: minrk

pandas/core/config_init.py

@@ -9,6 +9,7 @@
 module is imported, register them here rather then in the module.
 
 """
+import sys
 import warnings
 
 import pandas.core.config as cf
@@ -341,18 +342,36 @@ def mpl_style_cb(key):
 
 
 def table_schema_cb(key):
-    # Having _ipython_display_ defined messes with the return value
-    # from cells, so the Out[x] dictionary breaks.
-    # Currently table schema is the only thing using it, so we'll
-    # monkey patch `_ipython_display_` onto NDFrame when config option
-    # is set
-    # see https://github.com/pandas-dev/pandas/issues/16168
-    from pandas.core.generic import NDFrame, _ipython_display_
+    # first, check if we are in IPython
+    if 'IPython' not in sys.modules:
+        # definitely not in IPython
+        return
+    from IPython import get_ipython
+    ip = get_ipython()
+    if ip is None:
+        # still not in IPython
+        return
+
+    formatters = ip.display_formatter.formatters
+
+    mimetype = "application/vnd.dataresource+json"
 
     if cf.get_option(key):
-        NDFrame._ipython_display_ = _ipython_display_
-    elif getattr(NDFrame, '_ipython_display_', None):
-        del NDFrame._ipython_display_
+        if mimetype not in formatters:
+            # define tableschema formatter
+            from IPython.core.formatters import BaseFormatter
+
+            class TableSchemaFormatter(BaseFormatter):
+                print_method = '_repr_table_schema_'
+                _return_type = (dict,)
+            # register it:
+            formatters[mimetype] = TableSchemaFormatter()
+        # enable it if it's been disabled:
+        formatters[mimetype].enabled = True
+    else:
+        # unregister tableschema mime-type
+        if mimetype in formatters:
+            formatters[mimetype].enabled = False
 
 
 with cf.config_prefix('display'):

pandas/core/generic.py

@@ -43,7 +43,6 @@
 import pandas.core.algorithms as algos
 import pandas.core.common as com
 import pandas.core.missing as missing
-from pandas.errors import UnserializableWarning
 from pandas.io.formats.printing import pprint_thing
 from pandas.io.formats.format import format_percentiles
 from pandas.tseries.frequencies import to_offset
@@ -6279,38 +6278,6 @@ def logical_func(self, axis=None, bool_only=None, skipna=None, level=None,
     return set_function_name(logical_func, name, cls)
 
 
-def _ipython_display_(self):
-    # Having _ipython_display_ defined messes with the return value
-    # from cells, so the Out[x] dictionary breaks.
-    # Currently table schema is the only thing using it, so we'll
-    # monkey patch `_ipython_display_` onto NDFrame when config option
-    # is set
-    # see https://github.com/pandas-dev/pandas/issues/16168
-    try:
-        from IPython.display import display
-    except ImportError:
-        return None
-
-    # Series doesn't define _repr_html_ or _repr_latex_
-    latex = self._repr_latex_() if hasattr(self, '_repr_latex_') else None
-    html = self._repr_html_() if hasattr(self, '_repr_html_') else None
-    try:
-        table_schema = self._repr_table_schema_()
-    except Exception as e:
-        warnings.warn("Cannot create table schema representation. "
-                      "{}".format(e), UnserializableWarning)
-        table_schema = None
-    # We need the inital newline since we aren't going through the
-    # usual __repr__. See
-    # https://github.com/pandas-dev/pandas/pull/14904#issuecomment-277829277
-    text = "\n" + repr(self)
-
-    reprs = {"text/plain": text, "text/html": html, "text/latex": latex,
-             "application/vnd.dataresource+json": table_schema}
-    reprs = {k: v for k, v in reprs.items() if v}
-    display(reprs, raw=True)
-
-
 # install the indexes
 for _name, _indexer in indexing.get_indexers_list():
     NDFrame._create_indexer(_name, _indexer)

pandas/errors/__init__.py

@@ -57,9 +57,3 @@ class ParserWarning(Warning):
     """
 
 
-class UnserializableWarning(Warning):
-    """
-    Warning that is raised when a DataFrame cannot be serialized.
-
-    .. versionadded:: 0.20.0
-    """

pandas/tests/io/formats/test_printing.py

@@ -5,7 +5,6 @@
 import pandas as pd
 
 from pandas import compat
-from pandas.errors import UnserializableWarning
 import pandas.io.formats.printing as printing
 import pandas.io.formats.format as fmt
 import pandas.util.testing as tm
@@ -137,57 +136,46 @@ def setUpClass(cls):
             except ImportError:
                 pytest.skip("Mock is not installed")
         cls.mock = mock
+        from IPython.core.interactiveshell import InteractiveShell
+        cls.display_formatter = InteractiveShell.instance().display_formatter
 
     def test_publishes(self):
+
         df = pd.DataFrame({"A": [1, 2]})
         objects = [df['A'], df, df]  # dataframe / series
         expected_keys = [
             {'text/plain', 'application/vnd.dataresource+json'},
             {'text/plain', 'text/html', 'application/vnd.dataresource+json'},
         ]
 
-        make_patch = self.mock.patch('IPython.display.display')
         opt = pd.option_context('display.html.table_schema', True)
         for obj, expected in zip(objects, expected_keys):
-            with opt, make_patch as mock_display:
-                handle = obj._ipython_display_()
-                assert mock_display.call_count == 1
-                assert handle is None
-                args, kwargs = mock_display.call_args
-                arg, = args  # just one argument
-
-            assert kwargs == {"raw": True}
-            assert set(arg.keys()) == expected
+            with opt:
+                formatted = self.display_formatter.format(obj)
+            assert set(formatted[0].keys()) == expected
 
         with_latex = pd.option_context('display.latex.repr', True)
 
-        with opt, with_latex, make_patch as mock_display:
-            handle = obj._ipython_display_()
-            args, kwargs = mock_display.call_args
-            arg, = args
+        with opt, with_latex:
+            formatted = self.display_formatter.format(obj)
 
         expected = {'text/plain', 'text/html', 'text/latex',
                     'application/vnd.dataresource+json'}
-        assert set(arg.keys()) == expected
+        assert set(formatted[0].keys()) == expected
 
     def test_publishes_not_implemented(self):
         # column MultiIndex
         # GH 15996
         midx = pd.MultiIndex.from_product([['A', 'B'], ['a', 'b', 'c']])
         df = pd.DataFrame(np.random.randn(5, len(midx)), columns=midx)
 
-        make_patch = self.mock.patch('IPython.display.display')
         opt = pd.option_context('display.html.table_schema', True)
-        with opt, make_patch as mock_display:
-            with pytest.warns(UnserializableWarning) as record:
-                df._ipython_display_()
-                args, _ = mock_display.call_args
-                arg, = args  # just one argument
+
+        with opt:
+            formatted = self.display_formatter.format(df)
 
         expected = {'text/plain', 'text/html'}
-        assert set(arg.keys()) == expected
-        assert "orient='table' is not supported for MultiIndex" in (
-            record[-1].message.args[0])
+        assert set(formatted[0].keys()) == expected
 
     def test_config_on(self):
         df = pd.DataFrame({"A": [1, 2]})
@@ -209,26 +197,23 @@ def test_config_monkeypatches(self):
         assert not hasattr(df, '_ipython_display_')
         assert not hasattr(df['A'], '_ipython_display_')
 
+        formatters = self.display_formatter.formatters
+        mimetype = 'application/vnd.dataresource+json'
+
         with pd.option_context('display.html.table_schema', True):
-            assert hasattr(df, '_ipython_display_')
-            # smoke test that it works
-            df._ipython_display_()
-            assert hasattr(df['A'], '_ipython_display_')
-            df['A']._ipython_display_()
+            assert 'application/vnd.dataresource+json' in formatters
+            assert formatters[mimetype].enabled
 
-        assert not hasattr(df, '_ipython_display_')
-        assert not hasattr(df['A'], '_ipython_display_')
-        # re-unsetting is OK
-        assert not hasattr(df, '_ipython_display_')
-        assert not hasattr(df['A'], '_ipython_display_')
+        # still there, just disabled
+        assert 'application/vnd.dataresource+json' in formatters
+        assert not formatters[mimetype].enabled
 
         # able to re-set
         with pd.option_context('display.html.table_schema', True):
-            assert hasattr(df, '_ipython_display_')
+            assert 'application/vnd.dataresource+json' in formatters
+            assert formatters[mimetype].enabled
             # smoke test that it works
-            df._ipython_display_()
-            assert hasattr(df['A'], '_ipython_display_')
-            df['A']._ipython_display_()
+            self.display_formatter.format(cf)
 
 
 # TODO: fix this broken test