ENH: add parameter for HTML border (#14061)

Author: TomAugspurger

doc/source/options.rst

@@ -392,6 +392,9 @@ display.width              80           Width of the display in characters.
                                         IPython qtconsole, or IDLE do not run in a
                                         terminal and hence it is not possible
                                         to correctly detect the width.
+html.border                1            A ``border=value`` attribute is
+                                        inserted in the ``<table>`` tag
+                                        for the DataFrame HTML repr.
 io.excel.xls.writer        xlwt         The default Excel writer engine for
                                         'xls' files.
 io.excel.xlsm.writer       openpyxl     The default Excel writer engine for

doc/source/whatsnew/v0.19.0.txt

@@ -427,6 +427,7 @@ Other enhancements
      df.sort_values(by='row2', axis=1)
 
 - Added documentation to :ref:`I/O<io.dtypes>` regarding the perils of reading in columns with mixed dtypes and how to handle it (:issue:`13746`)
+- :meth:`~DataFrame.to_html` now has a ``border`` argument to control the value in the opening ``<table>`` tag. The default is the value of the ``html.border`` option, which defaults to 1. This also affects the notebook HTML repr, but since Jupyter's CSS includes a border-width attribute, the visual effect is the same. (:issue:`11563`).
 - Raise ``ImportError`` in the sql functions when ``sqlalchemy`` is not installed and a connection string is used (:issue:`11920`).
 - Compatibility with matplotlib 2.0. Older versions of pandas should also work with matplotlib 2.0 (:issue:`13333`)
 

pandas/core/config_init.py

@@ -346,6 +346,17 @@ def mpl_style_cb(key):
 cf.deprecate_option('display.height', msg=pc_height_deprecation_warning,
                     rkey='display.max_rows')
 
+pc_html_border_doc = """
+: int
+    A ``border=value`` attribute is inserted in the ``<table>`` tag
+    for the DataFrame HTML repr.
+"""
+
+with cf.config_prefix('html'):
+    cf.register_option('border', 1, pc_html_border_doc,
+                       validator=is_int)
+
+
 tc_sim_interactive_doc = """
 : boolean
     Whether to simulate interactive mode for purposes of testing

pandas/core/frame.py

@@ -1560,7 +1560,8 @@ def to_html(self, buf=None, columns=None, col_space=None, header=True,
                 index=True, na_rep='NaN', formatters=None, float_format=None,
                 sparsify=None, index_names=True, justify=None, bold_rows=True,
                 classes=None, escape=True, max_rows=None, max_cols=None,
-                show_dimensions=False, notebook=False, decimal='.'):
+                show_dimensions=False, notebook=False, decimal='.',
+                border=None):
         """
         Render a DataFrame as an HTML table.
 
@@ -1582,6 +1583,11 @@ def to_html(self, buf=None, columns=None, col_space=None, header=True,
             Character recognized as decimal separator, e.g. ',' in Europe
 
             .. versionadded:: 0.18.0
+        border : int
+            A ``border=border`` attribute is included in the opening
+            `<table>` tag. Default ``pd.options.html.border``.
+
+            .. versionadded:: 0.19.0
         """
 
         formatter = fmt.DataFrameFormatter(self, buf=buf, columns=columns,
@@ -1597,7 +1603,7 @@ def to_html(self, buf=None, columns=None, col_space=None, header=True,
                                            show_dimensions=show_dimensions,
                                            decimal=decimal)
         # TODO: a generic formatter wld b in DataFrameFormatter
-        formatter.to_html(classes=classes, notebook=notebook)
+        formatter.to_html(classes=classes, notebook=notebook, border=border)
 
         if buf is None:
             return formatter.buf.getvalue()

pandas/formats/format.py

@@ -671,20 +671,28 @@ def _format_col(self, i):
                             float_format=self.float_format, na_rep=self.na_rep,
                             space=self.col_space, decimal=self.decimal)
 
-    def to_html(self, classes=None, notebook=False):
+    def to_html(self, classes=None, notebook=False, border=None):
         """
         Render a DataFrame to a html table.
 
         Parameters
         ----------
+        classes : str or list-like
+            classes to include in the `class` attribute of the opening
+            ``<table>`` tag, in addition to the default "dataframe".
         notebook : {True, False}, optional, default False
             Whether the generated HTML is for IPython Notebook.
+        border : int
+            A ``border=border`` attribute is included in the opening
+            ``<table>`` tag. Default ``pd.options.html.border``.
 
-        """
+            .. versionadded:: 0.19.0
+         """
         html_renderer = HTMLFormatter(self, classes=classes,
                                       max_rows=self.max_rows,
                                       max_cols=self.max_cols,
-                                      notebook=notebook)
+                                      notebook=notebook,
+                                      border=border)
         if hasattr(self.buf, 'write'):
             html_renderer.write_result(self.buf)
         elif isinstance(self.buf, compat.string_types):
@@ -910,7 +918,7 @@ class HTMLFormatter(TableFormatter):
     indent_delta = 2
 
     def __init__(self, formatter, classes=None, max_rows=None, max_cols=None,
-                 notebook=False):
+                 notebook=False, border=None):
         self.fmt = formatter
         self.classes = classes
 
@@ -926,6 +934,9 @@ def __init__(self, formatter, classes=None, max_rows=None, max_cols=None,
         self.is_truncated = (self.max_rows < len(self.fmt.frame) or
                              self.max_cols < len(self.fmt.columns))
         self.notebook = notebook
+        if border is None:
+            border = get_option('html.border')
+        self.border = border
 
     def write(self, s, indent=0):
         rs = pprint_thing(s)
@@ -1001,7 +1012,8 @@ def write_result(self, buf):
 
             self.write('<div{0}>'.format(div_style))
 
-        self.write('<table border="1" class="%s">' % ' '.join(_classes),
+        self.write('<table border="%s" class="%s">' % (self.border,
+                                                       ' '.join(_classes)),
                    indent)
 
         indent += self.indent_delta

pandas/tests/formats/test_format.py

@@ -1650,6 +1650,23 @@ def test_to_html_truncate_multi_index_sparse_off(self):
             expected = expected.decode('utf-8')
         self.assertEqual(result, expected)
 
+    def test_to_html_border(self):
+        df = DataFrame({'A': [1, 2]})
+        result = df.to_html()
+        assert 'border="1"' in result
+
+    def test_to_html_border_option(self):
+        df = DataFrame({'A': [1, 2]})
+        with pd.option_context('html.border', 0):
+            result = df.to_html()
+            self.assertTrue('border="0"' in result)
+            self.assertTrue('border="0"' in df._repr_html_())
+
+    def test_to_html_border_zero(self):
+        df = DataFrame({'A': [1, 2]})
+        result = df.to_html(border=0)
+        self.assertTrue('border="0"' in result)
+
     def test_nonunicode_nonascii_alignment(self):
         df = DataFrame([["aa\xc3\xa4\xc3\xa4", 1], ["bbbb", 2]])
         rep_str = df.to_string()