Shorter repr for attributes

doc/whats-new.rst

@@ -41,6 +41,13 @@ By `Henry S. Harrison <https://hsharrison.github.io>`_.
   Note, the default is ``autoclose=False``, which is consistent with previous
   xarray behavior.  By `Phillip J. Wolfram <https://github.com/pwolfram>`_.
 
+- The ``repr()`` of ``Dataset`` and ``DataArray`` attributes uses a similar
+  format to coordinates and variables, with vertically aligned entries
+  truncated to fit on a single line.  Hopefully this will stop people writing
+  ``data.attrs = {}`` and discarding metadata in notebooks for the sake of
+  cleaner output.  The full metadata is still available as ``data.attrs``.
+  By `Zac Hatfield-Dodds <https://github.com/Zac-HD>`_.
+
 Bug fixes
 ~~~~~~~~~
 - ``rolling`` now keeps its original dimension order (:issue:`1125`).

xarray/core/formatting.py

@@ -253,8 +253,15 @@ def summarize_coord(name, var, col_width):
 
 
 def summarize_attr(key, value, col_width=None):
-    # ignore col_width for now to more clearly distinguish attributes
-    return u'    %s: %s' % (key, maybe_truncate(value))
+    """Summary for __repr__ - use ``X.attrs[key]`` for full value."""
+    # Indent key and add ':', then right-pad if col_width is not None
+    k_str = u'    %s:' % key
+    if col_width is not None:
+        k_str = pretty_print(k_str, col_width)
+    # Replace tabs and newlines, so we print on one line in known width
+    v_str = unicode_type(value).replace(u'\t', u'\\t').replace(u'\n', u'\\n')
+    # Finally, truncate to the desired display width
+    return maybe_truncate(u'%s %s' % (k_str, v_str), OPTIONS['display_width'])
 
 
 EMPTY_REPR = u'    *empty*'

xarray/tests/test_dataarray.py

@@ -49,7 +49,7 @@ def test_repr(self):
             other    int64 0
         Dimensions without coordinates: time
         Attributes:
-            foo: bar""")
+            foo:      bar""")
         self.assertEqual(expected, repr(data_array))
 
     def test_repr_multiindex(self):

xarray/tests/test_dataset.py

@@ -97,7 +97,7 @@ def test_repr(self):
             var2     (dim1, dim2) float64 1.162 -1.097 -2.123 1.04 -0.4034 -0.126 ...
             var3     (dim3, dim1) float64 0.5565 -0.2121 0.4563 1.545 -0.2397 0.1433 ...
         Attributes:
-            foo: bar""") % data['dim3'].dtype
+            foo:      bar""") % data['dim3'].dtype
         actual = '\n'.join(x.rstrip() for x in repr(data).split('\n'))
         print(actual)
         self.assertEqual(expected, actual)
@@ -183,7 +183,7 @@ def test_unicode_data(self):
         Data variables:
             *empty*
         Attributes:
-            å: ∑""" % u'ba®')
+            å:        ∑""" % u'ba®')
         actual = unicode_type(data)
         self.assertEqual(expected, actual)
 

xarray/tests/test_formatting.py

@@ -131,6 +131,17 @@ def test_format_timestamp_out_of_bounds(self):
         result = formatting.format_timestamp(date)
         self.assertEqual(result, expected)
 
+    def test_attribute_repr(self):
+        short = formatting.summarize_attr(u'key', u'Short string')
+        long = formatting.summarize_attr(u'key', 100 * u'Very long string ')
+        newlines = formatting.summarize_attr(u'key', u'\n\n\n')
+        tabs = formatting.summarize_attr(u'key', u'\t\t\t')
+        self.assertEqual(short, '    key: Short string')
+        self.assertLessEqual(len(long), 80)
+        self.assertTrue(long.endswith(u'...'))
+        self.assertNotIn(u'\n', newlines)
+        self.assertNotIn(u'\t', tabs)
+
 
 def test_set_numpy_options():
     original_options = np.get_printoptions()

xarray/tests/test_variable.py

@@ -644,7 +644,7 @@ def test_repr(self):
         array([[1, 2, 3],
                [4, 5, 6]])
         Attributes:
-            foo: bar
+            foo:      bar
         """).strip()
         self.assertEqual(expected, repr(v))