From b5f72b710d7ebdcefd2b5dddae38c2048ffd2382 Mon Sep 17 00:00:00 2001
From: Marshall Crumiller <mcrumiller@gmail.com>
Date: Thu, 25 Jul 2024 13:31:27 -0400
Subject: [PATCH 1/2] Add header align logic

---
 py-polars/polars/dataframe/frame.py             |  1 +
 py-polars/polars/io/spreadsheet/_write_utils.py | 15 +++++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/py-polars/polars/dataframe/frame.py b/py-polars/polars/dataframe/frame.py
index cf23828c420b..2e3803446e42 100644
--- a/py-polars/polars/dataframe/frame.py
+++ b/py-polars/polars/dataframe/frame.py
@@ -3190,6 +3190,7 @@ def write_excel(
             row_totals=row_totals,
             sparklines=sparklines,
             formulas=formulas,
+            autofilter=autofilter,
         )
 
         # normalise cell refs (eg: "B3" => (2,1)) and establish table start/finish,
diff --git a/py-polars/polars/io/spreadsheet/_write_utils.py b/py-polars/polars/io/spreadsheet/_write_utils.py
index 6509eaa54390..73ae79c9eba4 100644
--- a/py-polars/polars/io/spreadsheet/_write_utils.py
+++ b/py-polars/polars/io/spreadsheet/_write_utils.py
@@ -330,6 +330,7 @@ def _xl_setup_table_columns(
     row_totals: RowTotalsDefinition | None = None,
     float_precision: int = 3,
     table_style: dict[str, Any] | str | None = None,
+    autofilter: bool = True,  # noqa: FBT001
 ) -> tuple[list[dict[str, Any]], dict[str | tuple[str, ...], str], DataFrame]:
     """Setup and unify all column-related formatting/defaults."""
 
@@ -450,14 +451,23 @@ def _map_str(s: Series) -> Series:
         dtype_formats[tp] = fmt
 
     # associate formats/functions with specific columns
+    header_dict = header_format or {}
+    add_align = "align" not in header_dict
+    header_alignment = {"align": "right"} | ({"indent": 2} if autofilter else {})
+    col_header_format = {}
     for col, tp in df.schema.items():
         base_type = tp.base_type()
+        header_fmt = header_format
         if base_type in dtype_formats:
             fmt = dtype_formats.get(tp, dtype_formats[base_type])
             column_formats.setdefault(col, fmt)
+            if add_align and base_type in [*FLOAT_DTYPES, *INTEGER_DTYPES]:
+                header_fmt = header_dict | header_alignment
         if col not in column_formats:
             column_formats[col] = fmt_default
 
+        col_header_format[col] = format_cache.get(header_fmt) if header_fmt else None
+
     # ensure externally supplied formats are made available
     for col, fmt in column_formats.items():  # type: ignore[assignment]
         if isinstance(fmt, str):
@@ -473,9 +483,6 @@ def _map_str(s: Series) -> Series:
                 fmt["valign"] = "vcenter"
             column_formats[col] = format_cache.get(fmt)
 
-    # optional custom header format
-    col_header_format = format_cache.get(header_format) if header_format else None
-
     # assemble table columns
     table_columns = [
         {
@@ -483,7 +490,7 @@ def _map_str(s: Series) -> Series:
             for k, v in {
                 "header": col,
                 "format": column_formats[col],
-                "header_format": col_header_format,
+                "header_format": col_header_format.get(col),
                 "total_function": column_total_funcs.get(col),
                 "formula": (
                     row_total_funcs.get(col)

From c7cc745af2f0643d70d5d91d9c2122eb3b1a9c2c Mon Sep 17 00:00:00 2001
From: Marshall Crumiller <mcrumiller@gmail.com>
Date: Thu, 25 Jul 2024 13:51:53 -0400
Subject: [PATCH 2/2] No dict union for 3.8

---
 py-polars/polars/io/spreadsheet/_write_utils.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/py-polars/polars/io/spreadsheet/_write_utils.py b/py-polars/polars/io/spreadsheet/_write_utils.py
index 73ae79c9eba4..c659329d36cc 100644
--- a/py-polars/polars/io/spreadsheet/_write_utils.py
+++ b/py-polars/polars/io/spreadsheet/_write_utils.py
@@ -453,7 +453,9 @@ def _map_str(s: Series) -> Series:
     # associate formats/functions with specific columns
     header_dict = header_format or {}
     add_align = "align" not in header_dict
-    header_alignment = {"align": "right"} | ({"indent": 2} if autofilter else {})
+    header_alignment = {"align": "right"}
+    if autofilter:
+        header_alignment["indent"] = 2  # type: ignore[assignment]
     col_header_format = {}
     for col, tp in df.schema.items():
         base_type = tp.base_type()
@@ -462,7 +464,7 @@ def _map_str(s: Series) -> Series:
             fmt = dtype_formats.get(tp, dtype_formats[base_type])
             column_formats.setdefault(col, fmt)
             if add_align and base_type in [*FLOAT_DTYPES, *INTEGER_DTYPES]:
-                header_fmt = header_dict | header_alignment
+                header_fmt = {**header_dict, **header_alignment}
         if col not in column_formats:
             column_formats[col] = fmt_default