Files
CANveyor/stat/correlation.py
T

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Python

# File: correlation.py
# Copyright (C) 2026 Erick Ahmed
# SPDX-License-Identifier: AGPL-3.0-or-later
import argparse
from pathlib import Path
import numpy as np
import pandas as pd
import plotly.graph_objects as go
from utils.extractor import load_data
from utils.extractor import to_int
def calculate_correlation(df: pd.DataFrame, target_id: str | None = None) -> pd.DataFrame:
"""Calculates inter-byte correlation grouped by identifier."""
byte_cols = [f"b{i}" for i in range(8)]
available_cols = [col for col in byte_cols if col in df.columns]
if not available_cols:
raise ValueError("No byte columns (b0-b7) found in the DataFrame")
df_bytes = df[["Identifier"] + available_cols].copy()
for col in available_cols:
df_bytes[col] = df_bytes[col].apply(to_int)
if target_id:
group = df_bytes[df_bytes["Identifier"] == target_id]
if group.empty:
raise ValueError(f"Identifier '{target_id}' not found in data")
return group[available_cols].corr().fillna(0.0)
def max_abs_corr(group: pd.DataFrame) -> pd.Series:
corr_arr = np.abs(group.corr().to_numpy().copy())
np.fill_diagonal(corr_arr, 0.0)
return pd.Series(corr_arr.max(axis=0), index=group.columns).fillna(0.0)
return df_bytes.groupby("Identifier")[available_cols].apply(max_abs_corr)
def plot_correlation_heatmap(corr_df: pd.DataFrame, target_id: str | None, title: str) -> go.Figure:
"""Generates an interactive heatmap of inter-byte correlation."""
is_8x8 = target_id is not None
if is_8x8:
x = corr_df.columns.tolist()
y = corr_df.index.tolist()
z = corr_df.values
z_min, z_max = -1.0, 1.0
colorscale = [
[0.0, "#2c7bb6"], [0.25, "#abd9e9"], [0.5, "#ffffff"],
[0.75, "#fdae61"], [1.0, "#d7191c"]
]
hover_template = "<b>%{y}</b> vs <b>%{x}</b><br>Correlation: %{z:.2f}<extra></extra>"
else:
x = corr_df.columns.tolist()
y = corr_df.index.tolist()
z = corr_df.values
z_min, z_max = 0.0, 1.0
colorscale = [
[0.0, "#ffffff"], [0.2, "#fff5f0"], [0.4, "#fecc5c"],
[0.6, "#fd8d3c"], [0.8, "#e31a1c"], [1.0, "#800026"]
]
hover_template = "<b>%{y}</b><br>Byte %{x} max correlation: %{z:.2f}<extra></extra>"
fig = go.Figure(
data=go.Heatmap(
z=z, x=x, y=y,
zmin=z_min, zmax=z_max,
colorscale=colorscale,
xgap=3, ygap=3,
text=np.round(z, 2),
texttemplate="%{text}",
textfont={"size": 11, "color": "#2a2a2a", "family": "Segoe UI, Arial, sans-serif"},
hoverongaps=False,
hovertemplate=hover_template,
colorbar=dict(
title=dict(text="Correlation", side="top", font=dict(size=13, color="#1a1a1a")),
orientation="h", thickness=15, len=0.35,
x=1.0, xanchor="right", y=1.02, yanchor="bottom",
tickfont=dict(size=11, color="#2a2a2a"),
tickformat=".1f", outlinewidth=0.5, outlinecolor="#cccccc",
),
)
)
fig.update_layout(
title=dict(text=title, font=dict(size=20, color="#1a1a1a"), x=0.5, xanchor="center", pad=dict(b=20)),
height=max(600, len(y) * 28 + 150) if not is_8x8 else 600,
autosize=True,
template="plotly_white",
xaxis=dict(
title=dict(text="Byte Position", font=dict(size=13, color="#1a1a1a")),
side="top" if not is_8x8 else "bottom",
dtick=1, showgrid=False, linecolor="#bdbdbd",
tickfont=dict(size=12, color="#2a2a2a"), ticks="outside", ticklen=4, tickcolor="#cccccc",
),
yaxis=dict(
title=dict(text="PGN or CAN ID" if not is_8x8 else "Byte Position", font=dict(size=13, color="#1a1a1a")),
autorange="reversed", showgrid=False, linecolor="#bdbdbd",
tickfont=dict(size=12, color="#2a2a2a"), ticks="outside", ticklen=4, tickcolor="#cccccc", automargin=True,
),
font=dict(family="Segoe UI, Arial, sans-serif", size=12, color="#2a2a2a"),
hoverlabel=dict(bgcolor="white", font_size=13, font_family="Segoe UI", bordercolor="#cccccc"),
margin=dict(l=200, r=40, t=120, b=60),
)
return fig
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="Analyze CAN bus inter-byte correlation")
parser.add_argument("input", type=Path, help="Path to the input CAN log file")
parser.add_argument("output", type=Path, nargs="?", default=Path("correlation_report.html"), help="Path to the output HTML report")
parser.add_argument("title", nargs="?", default="CAN Bus Inter-Byte Correlation", help="Title for the HTML report")
parser.add_argument("--identifier", type=str, default=None, help="Specific PGN/CAN ID to analyze (e.g., 'PGN: 65331'). If omitted, shows max correlation per byte for all IDs.")
args = parser.parse_args()
df = load_data(args.input)
corr_df = calculate_correlation(df, target_id=args.identifier)
display_title = f"{args.title} ({args.identifier})" if args.identifier else args.title
fig = plot_correlation_heatmap(corr_df, target_id=args.identifier, title=display_title)
config = {
"responsive": True,
"displaylogo": False,
"scrollZoom": True,
"modeBarButtonsToAdd": ["toggleSpikelines"],
"toImageButtonOptions": {"format": "png", "scale": 2},
}
fig.write_html(str(args.output), include_plotlyjs="cdn", config=config)