Use to_string() to format DataFrames for clipboard.

Using str() has some unhelpful properties, especially when DataFrames
are large enough that the default repr does not show them in their
entirety. The defaults for to_string() are more helpful for the
clipboard.

Closes pandas-devgh-5346

Author: takluyver

pandas/io/clipboard.py

@@ -1,5 +1,5 @@
 """ io on the clipboard """
-from pandas import compat, get_option
+from pandas import compat, get_option, DataFrame
 from pandas.compat import StringIO
 
 def read_clipboard(**kwargs):  # pragma: no cover
@@ -64,5 +64,10 @@ def to_clipboard(obj, excel=None, sep=None, **kwargs):  # pragma: no cover
         except:
             pass
 
-    clipboard_set(str(obj))
+    if isinstance(obj, DataFrame):
+        # str(df) has various unhelpful defaults, like truncation
+        objstr = obj.to_string()
+    else:
+        objstr = str(obj)
+    clipboard_set(objstr)
 

pandas/io/tests/test_clipboard.py

@@ -7,6 +7,7 @@
 
 from pandas import DataFrame
 from pandas import read_clipboard
+from pandas import get_option
 from pandas.util import testing as tm
 from pandas.util.testing import makeCustomDataframe as mkdf
 
@@ -33,6 +34,11 @@ def setUpClass(cls):
         cls.data['mixed'] = DataFrame({'a': np.arange(1.0, 6.0) + 0.01,
                                        'b': np.arange(1, 6),
                                        'c': list('abcde')})
+        # Test GH-5346
+        max_rows = get_option('display.max_rows')
+        cls.data['longdf'] = mkdf(max_rows+1, 3, data_gen_f=lambda *args: randint(2),
+                                  c_idx_type='s', r_idx_type='i',
+                                  c_idx_names=[None], r_idx_names=[None])  
         cls.data_types = list(cls.data.keys())
 
     @classmethod