Leading space in to_string(index=False), #11833

doc/source/whatsnew/v0.18.0.txt

@@ -161,11 +161,33 @@ In addition, ``.round()`` will be available thru the ``.dt`` accessor of ``Serie
 
 .. _whatsnew_0180.api_breaking:
 
+- the leading whitespaces have been removed from the output of  ``to_string(index=False)``  method (:issue:'11833')
+
+Previous Behaviour for the DataFrame Objects
+
+.. code-block:: python
+
+   In [3]: df = pd.DataFrame({'a':range(5),'b':range(5)})
+   In [3]: df.to_string(index=False)
+   Out [4]: u' a  b\n 0  0\n 1  1\n 2  2\n 3  3\n 4  4'
+
+
+New Behaviour for the DataFrame Objects
+
+.. ipython:: python
+
+   df=pd.DataFrame({'a':range(5),'b':range(5)})
+   df.to_string(index=False)
+
+Similar behaviour applies for the Series objects as well.
+
 Backwards incompatible API changes
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 - The parameter ``out`` has been removed from the ``Series.round()`` method. (:issue:`11763`)
 - ``DataFrame.round()`` leaves non-numeric columns unchanged in its return, rather than raises. (:issue:`11885`)
+- ``DataFrame.head(0)`` and ``DataFrame.tail(0)`` return empty frames, rather than ``self``.  (:issue:`11937`)
+- ``Series.head(0)`` and ``Series.tail(0)`` return empty series, rather than ``self``.  (:issue:`11937`)
 
 NaT and Timedelta operations
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

pandas/core/format.py

@@ -245,7 +245,7 @@ def to_string(self):
         if self.index:
             result = self.adj.adjoin(3, *[fmt_index[1:], fmt_values])
         else:
-            result = self.adj.adjoin(3, fmt_values)
+            result = self.adj.adjoin(3, fmt_values).replace('\n ','\n').strip()
 
         if self.header and have_header:
             result = fmt_index[0] + '\n' + result
@@ -577,7 +577,8 @@ def to_string(self):
                 self._chk_truncate()
                 strcols = self._to_str_columns()
                 text = self.adj.adjoin(1, *strcols)
-
+        if not self.index:
+            text=text.replace('\n ','\n').strip()
         self.buf.writelines(text)
 
         if self.should_show_dimensions:

pandas/core/generic.py

@@ -2136,18 +2136,14 @@ def head(self, n=5):
         """
         Returns first n rows
         """
-        l = len(self)
-        if l == 0 or n==0:
-            return self
         return self.iloc[:n]
 
     def tail(self, n=5):
         """
         Returns last n rows
         """
-        l = len(self)
-        if l == 0 or n == 0:
-            return self
+        if n == 0:
+            return self.iloc[0:0]
         return self.iloc[-n:]
 
 

pandas/tests/test_format.py

@@ -1725,7 +1725,7 @@ def test_to_string_no_index(self):
                         'y': [4, 5, 6]})
 
         df_s = df.to_string(index=False)
-        expected = " x  y\n 1  4\n 2  5\n 3  6"
+        expected = "x  y\n1  4\n2  5\n3  6"
 
         self.assertEqual(df_s, expected)
 
@@ -3109,10 +3109,10 @@ def test_to_string_without_index(self):
         #GH 11729 Test index=False option
         s= Series([1, 2, 3, 4])
         result = s.to_string(index=False)
-        expected = (u(' 1\n') +
-                    ' 2\n' +
-                    ' 3\n' +
-                    ' 4')
+        expected = (u('1\n') +
+                    '2\n' +
+                    '3\n' +
+                    '4')
         self.assertEqual(result, expected)
 
     def test_unicode_name_in_footer(self):

pandas/tests/test_frame.py

@@ -5457,8 +5457,10 @@ def test_repr_column_name_unicode_truncation_bug(self):
     def test_head_tail(self):
         assert_frame_equal(self.frame.head(), self.frame[:5])
         assert_frame_equal(self.frame.tail(), self.frame[-5:])
-        assert_frame_equal(self.frame.head(0), self.frame)
-        assert_frame_equal(self.frame.tail(0), self.frame)
+
+        assert_frame_equal(self.frame.head(0), self.frame[0:0])
+        assert_frame_equal(self.frame.tail(0), self.frame[0:0])
+
         assert_frame_equal(self.frame.head(-1), self.frame[:-1])
         assert_frame_equal(self.frame.tail(-1), self.frame[1:])
         assert_frame_equal(self.frame.head(1), self.frame[:1])
@@ -5468,8 +5470,8 @@ def test_head_tail(self):
         df.index = np.arange(len(self.frame)) + 0.1
         assert_frame_equal(df.head(), df.iloc[:5])
         assert_frame_equal(df.tail(), df.iloc[-5:])
-        assert_frame_equal(df.head(0), df)
-        assert_frame_equal(df.tail(0), df)
+        assert_frame_equal(df.head(0), df[0:0])
+        assert_frame_equal(df.tail(0), df[0:0])
         assert_frame_equal(df.head(-1), df.iloc[:-1])
         assert_frame_equal(df.tail(-1), df.iloc[1:])
         #test empty dataframe

pandas/tests/test_generic.py

@@ -342,8 +342,8 @@ def test_head_tail(self):
             self._compare(o.tail(), o.iloc[-5:])
 
             # 0-len
-            self._compare(o.head(0), o.iloc[:])
-            self._compare(o.tail(0), o.iloc[0:])
+            self._compare(o.head(0), o.iloc[0:0])
+            self._compare(o.tail(0), o.iloc[0:0])
 
             # bounded
             self._compare(o.head(len(o)+1), o)

pandas/tests/test_series.py

@@ -7642,8 +7642,9 @@ def test_sortlevel(self):
 
     def test_head_tail(self):
         assert_series_equal(self.series.head(), self.series[:5])
+        assert_series_equal(self.series.head(0), self.series[0:0])
         assert_series_equal(self.series.tail(), self.series[-5:])
-
+        assert_series_equal(self.series.tail(0), self.series[0:0])
     def test_isin(self):
         s = Series(['A', 'B', 'C', 'a', 'B', 'B', 'A', 'C'])