API: allow option truncate for display.show_dimensions to only show dimensions if truncated (GH6457)

doc/source/release.rst

@@ -346,6 +346,8 @@ Improvements to existing features
 - Regression in the display of a MultiIndexed Series with ``display.max_rows`` is less than the
   length of the series (:issue:`7101`)
 - :meth:`~DataFrame.describe` now accepts an array of percentiles to include in the summary statistics (:issue:`4196`)
+- allow option ``'truncate'`` for ``display.show_dimensions`` to only show the dimensions if the
+  frame is truncated (:issue:`6547`)
 
 .. _release.bug_fixes-0.14.0:
 

doc/source/v0.14.0.txt

@@ -204,6 +204,26 @@ API changes
 Display Changes
 ~~~~~~~~~~~~~~~
 
+- allow option ``'truncate'`` for ``display.show_dimensions`` to only show the dimensions if the
+  frame is truncated (:issue:`6547`).
+
+  The default for ``display.show_dimensions`` will now be **truncate**! This is consistent with
+  how Series display length.
+
+  .. ipython:: python
+
+     dfd = pd.DataFrame(np.arange(25).reshape(-1,5), index=[0,1,2,3,4], columns=[0,1,2,3,4])
+
+     # show dimensions only if truncated
+     with pd.option_context('display.max_rows', 2, 'display.max_columns', 2,
+                            'display.show_dimensions', 'truncate'):
+        print(dfd)
+
+     # show dimensions only if truncated
+     with pd.option_context('display.max_rows', 10, 'display.max_columns', 40,
+                            'display.show_dimensions', 'truncate'):
+        print(dfd)
+
 - Regression in the display of a MultiIndexed Series with ``display.max_rows`` is less than the
   length of the series (:issue:`7101`)
 - Fixed a bug in the HTML repr of a truncated Series or DataFrame not showing the class name with the

pandas/core/config_init.py

@@ -120,8 +120,10 @@
 """
 
 pc_show_dimensions_doc = """
-: boolean
+: boolean or 'truncate'
     Whether to print out dimensions at the end of DataFrame repr.
+    If 'truncate' is specified, only print out the dimensions if the
+    frame is truncated (e.g. not display all rows and/or columns)
 """
 
 pc_line_width_doc = """
@@ -247,7 +249,8 @@ def mpl_style_cb(key):
     cf.register_option('encoding', detect_console_encoding(), pc_encoding_doc,
                        validator=is_text)
     cf.register_option('expand_frame_repr', True, pc_expand_repr_doc)
-    cf.register_option('show_dimensions', True, pc_show_dimensions_doc)
+    cf.register_option('show_dimensions', True, pc_show_dimensions_doc,
+                       validator=is_one_of_factory([True, False, 'truncate']))
     cf.register_option('chop_threshold', None, pc_chop_threshold_doc)
     cf.register_option('max_seq_items', 100, pc_max_seq_items)
     cf.register_option('mpl_style', None, pc_mpl_style_doc,

pandas/core/format.py

@@ -236,6 +236,12 @@ def _strlen(x):
 
 
 class TableFormatter(object):
+    is_truncated = False
+    show_dimensions = None
+
+    @property
+    def should_show_dimensions(self):
+        return self.show_dimensions is True or (self.show_dimensions == 'truncate' and self.is_truncated)
 
     def _get_formatter(self, i):
         if isinstance(self.formatters, (list, tuple)):
@@ -315,9 +321,9 @@ def _to_str_columns(self):
         _strlen = _strlen_func()
 
         cols_to_show = self.columns[:self.max_cols]
-        truncate_h = self.max_cols and (len(self.columns) > self.max_cols)
-        truncate_v = self.max_rows and (len(self.frame) > self.max_rows)
-        self.truncated_v = truncate_v
+        self.truncated_h = truncate_h = self.max_cols and (len(self.columns) > self.max_cols)
+        self.truncated_v = truncate_v = self.max_rows and (len(self.frame) > self.max_rows)
+        self.is_truncated = self.truncated_h or self.truncated_v
         if truncate_h:
             cols_to_show = self.columns[:self.max_cols]
         else:
@@ -380,7 +386,7 @@ def to_string(self):
 
         self.buf.writelines(text)
 
-        if self.show_dimensions:
+        if self.should_show_dimensions:
             self.buf.write("\n\n[%d rows x %d columns]"
                            % (len(frame), len(frame.columns)))
 
@@ -634,6 +640,8 @@ def __init__(self, formatter, classes=None, max_rows=None, max_cols=None):
 
         self.max_rows = max_rows or len(self.fmt.frame)
         self.max_cols = max_cols or len(self.fmt.columns)
+        self.show_dimensions = self.fmt.show_dimensions
+        self.is_truncated = self.max_rows < len(self.fmt.frame) or self.max_cols < len(self.fmt.columns)
 
     def write(self, s, indent=0):
         rs = com.pprint_thing(s)
@@ -709,7 +717,7 @@ def write_result(self, buf):
         indent = self._write_body(indent)
 
         self.write('</table>', indent)
-        if self.fmt.show_dimensions:
+        if self.should_show_dimensions:
             by = chr(215) if compat.PY3 else unichr(215)  # ×
             self.write(u('<p>%d rows %s %d columns</p>') %
                        (len(frame), by, len(frame.columns)))

pandas/tests/test_format.py

@@ -1197,6 +1197,26 @@ def test_to_string_line_width(self):
         s = df.to_string(line_width=80)
         self.assertEqual(max(len(l) for l in s.split('\n')), 80)
 
+    def test_show_dimensions(self):
+        df = pd.DataFrame(123, lrange(10, 15), lrange(30))
+
+        with option_context('display.max_rows', 10, 'display.max_columns', 40, 'display.width',
+                            500, 'display.expand_frame_repr', 'info', 'display.show_dimensions', True):
+            self.assertTrue('5 rows' in str(df))
+            self.assertTrue('5 rows' in df._repr_html_())
+        with option_context('display.max_rows', 10, 'display.max_columns', 40, 'display.width',
+                            500, 'display.expand_frame_repr', 'info', 'display.show_dimensions', False):
+            self.assertFalse('5 rows' in str(df))
+            self.assertFalse('5 rows' in df._repr_html_())
+        with option_context('display.max_rows', 2, 'display.max_columns', 2, 'display.width',
+                            500, 'display.expand_frame_repr', 'info', 'display.show_dimensions', 'truncate'):
+            self.assertTrue('5 rows' in str(df))
+            self.assertTrue('5 rows' in df._repr_html_())
+        with option_context('display.max_rows', 10, 'display.max_columns', 40, 'display.width',
+                            500, 'display.expand_frame_repr', 'info', 'display.show_dimensions', 'truncate'):
+            self.assertFalse('5 rows' in str(df))
+            self.assertFalse('5 rows' in df._repr_html_())
+
     def test_to_html(self):
         # big mixed
         biggie = DataFrame({'A': randn(200),