Normalize CAN IDs to strictly match same number of bit

stat/entropy.py

@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 import argparse
+import numbers
 from pathlib import Path
 
 import numpy as np
@@ -12,6 +13,21 @@ import plotly.graph_objects as go
 from utils.extractor import load_data
 from utils.extractor import to_int
 
+def _format_can_id(x):
+    if pd.isna(x):
+        return "UNKNOWN"
+    if isinstance(x, numbers.Number):
+        return f"{int(x):08X}"
+    s = str(x).strip()
+    if s.lower().startswith('0x'):
+        s = s[2:]
+    if s.isdigit():
+        return f"{int(s):08X}"
+    try:
+        return f"{int(s, 16):08X}"
+    except ValueError:
+        return s
+
 def calculate_byte_entropy(df: pd.DataFrame) -> pd.DataFrame:
     """Calculates Shannon entropy per byte position for each identifier."""
     byte_cols = [f"b{i}" for i in range(8)]
@@ -19,6 +35,9 @@ def calculate_byte_entropy(df: pd.DataFrame) -> pd.DataFrame:
     if not available_cols:
         raise ValueError("No byte columns (b0-b7) found in the DataFrame")
 
+    can_id_col = 'ID' if 'ID' in df.columns else 'Identifier'
+    identifiers = df[can_id_col].apply(_format_can_id)
+
     df_bytes = df[available_cols].copy()
     for col in available_cols:
         df_bytes[col] = df_bytes[col].apply(to_int)
@@ -30,8 +49,9 @@ def calculate_byte_entropy(df: pd.DataFrame) -> pd.DataFrame:
         p = s.value_counts(normalize=True)
         return -np.sum(p * np.log2(p))
 
-    return df.groupby("Identifier")[available_cols].agg(entropy)
-
+    result = df_bytes.groupby(identifiers).agg(entropy)
+    result.index.name = 'Identifier'
+    return result
 
 def plot_entropy_heatmap(entropy_df: pd.DataFrame, title: str) -> go.Figure:
     """Generates an interactive heatmap of byte-level Shannon entropy."""
@@ -131,7 +151,6 @@ def plot_entropy_heatmap(entropy_df: pd.DataFrame, title: str) -> go.Figure:
     )
     return fig
 
-
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(
         description="Analyze CAN bus byte-level entropy"