From 06d42ab0b3671ec9c064e322581081e51effcfa4 Mon Sep 17 00:00:00 2001
From: Stefan Siegel <ssiegel@sdas.net>
Date: Thu, 7 Nov 2024 15:46:54 +0100
Subject: [PATCH] fix: Convert MultiIndex columns to string representation

Previously, report generation failed for DataFrames with a MultiIndex on
the column axis due to a "TypeError: Setting a MultiIndex dtype to
anything other than object is not supported."
This update converts all indexes to their string representation: simple
indexes remain unchanged, while MultiIndexes are represented in a
tuple-style format.
---
 .../model/pandas/dataframe_pandas.py          |  2 +-
 tests/unit/test_multiindex_columns.py         | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 tests/unit/test_multiindex_columns.py

diff --git a/src/ydata_profiling/model/pandas/dataframe_pandas.py b/src/ydata_profiling/model/pandas/dataframe_pandas.py
index 2a6ebbbab..bb5be516b 100644
--- a/src/ydata_profiling/model/pandas/dataframe_pandas.py
+++ b/src/ydata_profiling/model/pandas/dataframe_pandas.py
@@ -32,5 +32,5 @@ def pandas_preprocess(config: Settings, df: pd.DataFrame) -> pd.DataFrame:
     df = rename_index(df)
 
     # Ensure that columns are strings
-    df.columns = df.columns.astype("str")
+    df.columns = df.columns.map(str)
     return df
diff --git a/tests/unit/test_multiindex_columns.py b/tests/unit/test_multiindex_columns.py
new file mode 100644
index 000000000..3d9558968
--- /dev/null
+++ b/tests/unit/test_multiindex_columns.py
@@ -0,0 +1,20 @@
+import pandas as pd
+import pytest
+
+from ydata_profiling import ProfileReport
+
+
+@pytest.fixture()
+def df():
+    df = pd.DataFrame(
+        {
+            ("foo", "one"): [1, 2, 3],
+            ("bar", "two"): [4, 5, 6],
+        }
+    )
+    return df
+
+
+def test_multiindex_columns(df: pd.DataFrame):
+    profile_report = ProfileReport(df, title="Test Report", progress_bar=False)
+    assert len(profile_report.to_html()) > 0