BUG-22984 Fix truncation of DataFrame representations (#22987)

* BUG-22984 Fix truncation of DataFrame representations

Author: JustinZhengBC

doc/source/whatsnew/v0.24.0.rst

@@ -1319,7 +1319,8 @@ Notice how we now instead output ``np.nan`` itself instead of a stringified form
 - :func:`read_sas()` will correctly parse sas7bdat files with many columns (:issue:`22628`)
 - :func:`read_sas()` will correctly parse sas7bdat files with data page types having also bit 7 set (so page type is 128 + 256 = 384) (:issue:`16615`)
 - Bug in :meth:`detect_client_encoding` where potential ``IOError`` goes unhandled when importing in a mod_wsgi process due to restricted access to stdout. (:issue:`21552`)
-- Bug in :func:`to_string()` that broke column alignment when ``index=False`` and width of first column's values is greater than the width of first column's header (:issue:`16839`, :issue:`13032`)
+- Bug in :func:`DataFrame.to_string()` that broke column alignment when ``index=False`` and width of first column's values is greater than the width of first column's header (:issue:`16839`, :issue:`13032`)
+- Bug in :func:`DataFrame.to_string()` that caused representations of :class:`DataFrame` to not take up the whole window (:issue:`22984`)
 - Bug in :func:`DataFrame.to_csv` where a single level MultiIndex incorrectly wrote a tuple. Now just the value of the index is written (:issue:`19589`).
 - Bug in :meth:`HDFStore.append` when appending a :class:`DataFrame` with an empty string column and ``min_itemsize`` < 8 (:issue:`12242`)
 - Bug in :meth:`read_csv()` in which :class:`MultiIndex` index names were being improperly handled in the cases when they were not provided (:issue:`23484`)

pandas/io/formats/format.py

@@ -608,11 +608,6 @@ def to_string(self):
             else:  # max_cols == 0. Try to fit frame to terminal
                 text = self.adj.adjoin(1, *strcols).split('\n')
                 max_len = Series(text).str.len().max()
-                headers = [ele[0] for ele in strcols]
-                # Size of last col determines dot col size. See
-                # `self._to_str_columns
-                size_tr_col = len(headers[self.tr_size_col])
-                max_len += size_tr_col  # Need to make space for largest row
                 # plus truncate dot col
                 dif = max_len - self.w
                 # '+ 1' to avoid too wide repr (GH PR #17023)

pandas/tests/io/formats/test_format.py

@@ -305,14 +305,10 @@ def test_repr_non_interactive(self):
             assert not has_truncated_repr(df)
             assert not has_expanded_repr(df)
 
-    def test_repr_truncates_terminal_size(self):
+    def test_repr_truncates_terminal_size(self, mock):
         # https://github.com/pandas-dev/pandas/issues/21180
         # TODO: use mock fixutre.
         # This is being backported, so doing it directly here.
-        try:
-            from unittest import mock
-        except ImportError:
-            mock = pytest.importorskip("mock")
 
         terminal_size = (118, 96)
         p1 = mock.patch('pandas.io.formats.console.get_terminal_size',
@@ -343,6 +339,17 @@ def test_repr_truncates_terminal_size(self):
 
         assert df2.columns[0] in result.split('\n')[0]
 
+    def test_repr_truncates_terminal_size_full(self, mock):
+        # GH 22984 ensure entire window is filled
+        terminal_size = (80, 24)
+        df = pd.DataFrame(np.random.rand(1, 7))
+        p1 = mock.patch('pandas.io.formats.console.get_terminal_size',
+                        return_value=terminal_size)
+        p2 = mock.patch('pandas.io.formats.format.get_terminal_size',
+                        return_value=terminal_size)
+        with p1, p2:
+            assert "..." not in str(df)
+
     def test_repr_max_columns_max_rows(self):
         term_width, term_height = get_terminal_size()
         if term_width < 10 or term_height < 10: