Add DataFrame usage guide with HTML rendering customization options

docs/source/user-guide/basics.rst

@@ -72,6 +72,8 @@ DataFrames are typically created by calling a method on :py:class:`~datafusion.c
 calling the transformation methods, such as :py:func:`~datafusion.dataframe.DataFrame.filter`, :py:func:`~datafusion.dataframe.DataFrame.select`, :py:func:`~datafusion.dataframe.DataFrame.aggregate`,
 and :py:func:`~datafusion.dataframe.DataFrame.limit` to build up a query definition.
 
+For more details on working with DataFrames, including visualization options and conversion to other formats, see :doc:`dataframe`.
+
 Expressions
 -----------
 

docs/source/user-guide/dataframe.rst

@@ -0,0 +1,179 @@
+.. Licensed to the Apache Software Foundation (ASF) under one
+.. or more contributor license agreements.  See the NOTICE file
+.. distributed with this work for additional information
+.. regarding copyright ownership.  The ASF licenses this file
+.. to you under the Apache License, Version 2.0 (the
+.. "License"); you may not use this file except in compliance
+.. with the License.  You may obtain a copy of the License at
+
+..   http://www.apache.org/licenses/LICENSE-2.0
+
+.. Unless required by applicable law or agreed to in writing,
+.. software distributed under the License is distributed on an
+.. "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+.. KIND, either express or implied.  See the License for the
+.. specific language governing permissions and limitations
+.. under the License.
+
+DataFrames
+==========
+
+Overview
+--------
+
+DataFusion's DataFrame API provides a powerful interface for building and executing queries against data sources. 
+It offers a familiar API similar to pandas and other DataFrame libraries, but with the performance benefits of Rust 
+and Arrow.
+
+A DataFrame represents a logical plan that can be composed through operations like filtering, projection, and aggregation.
+The actual execution happens when terminal operations like `collect()` or `show()` are called.
+
+Basic Usage
+----------
+
+.. code-block:: python
+
+    import datafusion
+    from datafusion import col, lit
+
+    # Create a context and register a data source
+    ctx = datafusion.SessionContext()
+    ctx.register_csv("my_table", "path/to/data.csv")
+
+    # Create and manipulate a DataFrame
+    df = ctx.sql("SELECT * FROM my_table")
+
+    # Or use the DataFrame API directly
+    df = (ctx.table("my_table")
+          .filter(col("age") > lit(25))
+          .select([col("name"), col("age")]))
+
+    # Execute and collect results
+    result = df.collect()
+
+    # Display the first few rows
+    df.show()
+
+HTML Rendering
+-------------
+
+When working in Jupyter notebooks or other environments that support HTML rendering, DataFrames will
+automatically display as formatted HTML tables, making it easier to visualize your data.
+
+The `_repr_html_` method is called automatically by Jupyter to render a DataFrame. This method 
+controls how DataFrames appear in notebook environments, providing a richer visualization than
+plain text output.
+
+Customizing HTML Rendering
+-------------------------
+
+You can customize how DataFrames are rendered in HTML by configuring the formatter:
+
+.. code-block:: python
+
+    from datafusion.html_formatter import configure_formatter
+
+    # Change the default styling
+    configure_formatter(
+        max_rows=50,           # Maximum number of rows to display
+        max_width=None,        # Maximum width in pixels (None for auto)
+        theme="light",         # Theme: "light" or "dark" 
+        precision=2,           # Floating point precision
+        thousands_separator=",", # Separator for thousands
+        date_format="%Y-%m-%d", # Date format
+        truncate_width=20      # Max width for string columns before truncating
+    )
+
+The formatter settings affect all DataFrames displayed after configuration.
+
+Custom Style Providers
+---------------------
+
+For advanced styling needs, you can create a custom style provider:
+
+.. code-block:: python
+
+    from datafusion.html_formatter import StyleProvider, configure_formatter
+
+    class MyStyleProvider(StyleProvider):
+        def get_table_styles(self):
+            return {
+                "table": "border-collapse: collapse; width: 100%;",
+                "th": "background-color: #007bff; color: white; padding: 8px; text-align: left;",
+                "td": "border: 1px solid #ddd; padding: 8px;",
+                "tr:nth-child(even)": "background-color: #f2f2f2;",
+            }
+
+        def get_value_styles(self, dtype, value):
+            """Return custom styles for specific values"""
+            if dtype == "float" and value < 0:
+                return "color: red;"
+            return None
+
+    # Apply the custom style provider
+    configure_formatter(style_provider=MyStyleProvider())
+
+Creating a Custom Formatter
+--------------------------
+
+For complete control over rendering, you can implement a custom formatter:
+
+.. code-block:: python
+
+    from datafusion.html_formatter import Formatter, get_formatter
+
+    class MyFormatter(Formatter):
+        def format_html(self, batches, schema, has_more=False, table_uuid=None):
+            # Create your custom HTML here
+            html = "<div class='my-custom-table'>"
+            # ... formatting logic ...
+            html += "</div>"
+            return html
+
+    # Set as the global formatter
+    configure_formatter(formatter_class=MyFormatter)
+
+    # Or use the formatter just for specific operations
+    formatter = get_formatter()
+    custom_html = formatter.format_html(batches, schema)
+
+Managing Formatters
+------------------
+
+Reset to default formatting:
+
+.. code-block:: python
+
+    from datafusion.html_formatter import reset_formatter
+
+    # Reset to default settings
+    reset_formatter()
+
+Get the current formatter settings:
+
+.. code-block:: python
+
+    from datafusion.html_formatter import get_formatter
+
+    formatter = get_formatter()
+    print(formatter.max_rows)
+    print(formatter.theme)
+
+Contextual Formatting
+--------------------
+
+You can also use a context manager to temporarily change formatting settings:
+
+.. code-block:: python
+
+    from datafusion.html_formatter import formatting_context
+
+    # Default formatting
+    df.show()
+
+    # Temporarily use different formatting
+    with formatting_context(max_rows=100, theme="dark"):
+        df.show()  # Will use the temporary settings
+
+    # Back to default formatting
+    df.show()