Added extra info section to EA repr

pandas/core/arrays/base.py

@@ -53,6 +53,7 @@ class ExtensionArray(object):
 
     * __repr__ : A default repr for the ExtensionArray.
     * _formatter : Print scalars inside a Series or DataFrame.
+    * _repr_extra : Extra information to be included in the default repr.
 
     Some methods require casting the ExtensionArray to an ndarray of Python
     objects with ``self.astype(object)``, which may be expensive. When
@@ -699,17 +700,21 @@ def __repr__(self):
         template = (
             u'{class_name}'
             u'{data}\n'
-            u'Length: {length}, dtype: {dtype}'
+            u'Length: {length}, dtype: {dtype}{extra}'
         )
         # the short repr has no trailing newline, while the truncated
         # repr does. So we include a newline in our template, and strip
         # any trailing newlines from format_object_summary
         data = format_object_summary(self, self._formatter(),
                                      indent_for_name=False).rstrip(', \n')
         class_name = u'<{}>\n'.format(self.__class__.__name__)
+        extra = self._repr_extra()
+        if extra:
+            extra = ', {}'.format(extra)
         return template.format(class_name=class_name, data=data,
                                length=len(self),
-                               dtype=self.dtype)
+                               dtype=self.dtype,
+                               extra=extra)
 
     def _formatter(self, boxed=False):
         # type: (bool) -> Callable[[Any], Optional[str]]
@@ -739,6 +744,20 @@ def _formatter(self, boxed=False):
             return str
         return repr
 
+    def _repr_extra(self):
+        """
+        Additional text to be placed into the default repr.
+
+        This text is placed after the ``dtype: <dtype>``, section
+        of the repr, and is separated by a comma and a space.
+
+        Returns
+        -------
+        str:
+            The additional text to be included in the repr.
+        """
+        return ''
+
     def _formatting_values(self):
         # type: () -> np.ndarray
         # At the moment, this has to be an array since we use result.dtype

pandas/tests/extension/decimal/array.py

@@ -144,6 +144,9 @@ def _reduce(self, name, skipna=True, **kwargs):
                                       "the {} operation".format(name))
         return op(axis=0)
 
+    def _repr_extra(self):
+        return 'prec: {}'.format(self.dtype.context.prec)
+
 
 def to_decimal(values, context=None):
     return DecimalArray([decimal.Decimal(x) for x in values], context=context)

pandas/tests/extension/decimal/test_decimal.py

@@ -399,3 +399,14 @@ def _formatting_values(self):
     with tm.assert_produces_warning(DeprecationWarning,
                                     check_stacklevel=check_stacklevel):
         repr(ser)
+
+
+def test_repr():
+    arr = to_decimal(([1, 2, 3]))
+    result = repr(arr)
+    expected = (
+        "<DecimalArray>\n"
+        "[Decimal('1'), Decimal('2'), Decimal('3')]\n"
+        "Length: 3, dtype: decimal, prec: 28"
+    )
+    assert result == expected