gg-diagram

Publication-quality GG diagrams for vehicle dynamics analysis.

Plot lateral vs longitudinal acceleration as distance-weighted heatmaps. Based on the GG diagram concept from Milliken & Milliken's Race Car Vehicle Dynamics (1995).

Real driving data (AEGIS dataset, 81 km, Graz, Austria). Left: raw IMU signal with gravity bias. Right: after in-field calibration -- the acceleration cloud is centered and aligned with the vehicle axes.

Installation

pip install gg-diagram

Quick Start

import pandas as pd
from gg_diagram import gg_heatmap

df = pd.read_parquet("my_driving_data.parquet")

fig = gg_heatmap(df, ax_col="ax_mps2", ay_col="ay_mps2", speed_col="speed_mps")
fig.show()

Features

• Distance-weighted heatmap -- bins weighted by speed * dt, not sample count
• Log scale -- reveals both high-density core and low-density tails
• Publication style -- directional axis labels (Braking/Acceleration, Right/Left Turn), external contour, automotive colorscale
• Before/After comparison -- gg_compare() with shared color axis
• Two modes -- mode="interactive" (rich hover) or mode="paper" (compact for export)
• Auto unit detection -- accepts m/s2, g, or mG
• Variable frequency -- computes dt from timestamps (handles multi-rate datasets)

API

gg_heatmap(df, ...)

Single GG diagram.

fig = gg_heatmap(
    df,
    ax_col="ax_mps2",       # longitudinal acceleration column
    ay_col="ay_mps2",       # lateral acceleration column
    speed_col="speed_mps",  # speed in m/s (for distance weighting)
    ts_col="ts",            # timestamp column (for variable dt)
    hz=10.0,                # fallback frequency if no timestamps
    title="My GG Diagram",
    mode="interactive",     # or "paper"
    output_html="gg.html",  # optional HTML export
)

gg_compare(df_before, df_after, ...)

Side-by-side comparison with shared color scale.

fig = gg_compare(
    df_before, df_after,
    title_before="Raw",
    title_after="Calibrated",
    main_title="IMU Rectification",
    mode="paper",
    output_html="compare.html",
)

gg_scatter(df, ...)

Scatter plot with optional speed coloring.

fig = gg_scatter(df, color_col="speed_mps")

Metrics

Each figure exposes severity metrics via fig._gg_meta:

fig._gg_meta["std_gx"]             # Std of longitudinal acceleration (g)
fig._gg_meta["std_gy"]             # Std of lateral acceleration (g)
fig._gg_meta["total_distance_km"]  # Total distance (km)

Data Format

The package expects a pandas DataFrame with at minimum:

Column names are configurable via ax_col, ay_col, speed_col, ts_col.

Links

• Research: research.roadsimulator3.fr
• Simulator: simulate.roadsimulator3.fr
• Author: Sebastien Edet

License

MIT