modify logic and change docstring

Author: charlesdong1991

pandas/core/generic.py

@@ -2910,9 +2910,11 @@ def to_csv(self, path_or_buf=None, sep=",", na_rep='', float_format=None,
 
         index : bool, default True
             Write row names (index).
-        index_label : str or sequence, or False, default None
+        index_label : False or str or sequence, default None
             Column label for index column(s) if desired. If None is given, and
-            `header` and `index` are True, then the index names are used. A
+            `header` and `index` are True, then the index names are used. If
+            `header` is False or None, default index_label changes to False,
+            neither header nor index names will be printed. A
             sequence should be given if the object uses MultiIndex. If
             False do not print fields for index names. Use index_label=False
             for easier importing in R.

pandas/io/formats/csvs.py

@@ -53,8 +53,8 @@ def __init__(self, obj, path_or_buf=None, sep=",", na_rep='',
         self.index_label = index_label
         # set defualt index label to False if header is False and
         # index_label is not None or False.
-        if not self.header:
-            if not self.index_label:
+        if self.header is None or self.header is False:
+            if self.index_label is None:
                 self.index_label = False
         self.mode = mode
         if encoding is None:

pandas/tests/generic/test_frame.py

@@ -274,7 +274,7 @@ def test_deepcopy_empty(self):
     @pytest.mark.skipif(os.name == 'nt',
                         reason="Windows use \r\n for newline")
     @pytest.mark.parametrize("header, index_label, expected", [
-        (False, None, 'index.name,,\n0,0,0\n1,0,0\n'),
+        (False, None, '0,0,0\n1,0,0\n'),
         (True, None, 'index.name,0,1\n0,0,0\n1,0,0\n'),
         (False, False, '0,0,0\n1,0,0\n'),
         (True, False, ',0,1\n0,0,0\n1,0,0\n')
@@ -290,7 +290,7 @@ def test_to_csv_header_single_index(self, header, index_label, expected):
     @pytest.mark.skipif(os.name == 'nt',
                         reason="Windows use \r\n for newline")
     @pytest.mark.parametrize("header, index_label, expected", [
-        (False, None, 'index.name.0,index.name.1,,\na,b,0,0\na,c,0,0\n'),
+        (False, None, 'a,b,0,0\na,c,0,0\n'),
         (True, None, 'index.name.0,index.name.1,0,1\na,b,0,0\na,c,0,0\n'),
         (False, False, 'a,b,0,0\na,c,0,0\n'),
         (True, False, ',,0,1\na,b,0,0\na,c,0,0\n')