quantile-cube 0.1.3

Triangular heatmap for visualizing quantile-based distributions and signed effects across a 2D velocity–acceleration space with multi-dimensional angle encoding.

quantile-cube

A Python package for visualizing the distribution of 3D movement data — velocity, acceleration, and angle — collapsed into a 2D heatmap.

Movement observations are binned into quantiles along three dimensions: velocity (x-axis), acceleration (y-axis), and angle of movement (the four triangles within each cell).

Color intensity reflects the value associated with each bin, which may represent:

• relative density (proportion of observations),
• signed effect size (positive or negative values),
• or normalized magnitude depending on the input data.

This enables comparison of movement structure across velocity, acceleration, and angle dimensions under multiple statistical interpretations.

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Table of Contents

• Installation
• Quick Start
• Parameters
• Advanced Usage
• How It Works
• Contributing
• Citation
• License

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Installation

Install from PyPI (no repo cloning needed):

pip install quantile-cube

Requirements: Python 3.9+, NumPy ≥ 1.21, Matplotlib ≥ 3.5, Pandas ≥ 1.3

If you'd like to explore the source, run examples, or contribute:

git clone https://github.com/kelanethomas/quantile-cube.git
cd quantile-cube
pip install -e .

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Quick Start

Option 1 — Raw arrays

from quantile_cube import plot_cube
import numpy as np

q1 = np.random.rand(25)
q2 = np.random.rand(25)
q3 = np.random.rand(25)
q4 = np.random.rand(25)

plot_cube(
    values=[q1, q2, q3, q4],
    M=5,
    N=5,
    title="My Quantile Cube",
    colorbar_label="Value",
    cmap="Blues",
)

Option 2 — DataFrame (recommended)

If your data is in a DataFrame with columns named like Q1_vel_Q1_acc_Q1_angle:

from quantile_cube import plot_cube

plot_cube(
    cube_data=df,
    M=5,
    N=5,
    title="Game 5 Quantile Cube",
)

Note: If your data contains both positive and negative values, a diverging colormap such as "RdBu_r" is recommended for correct visual interpretation.

Parameters

Parameter	Type	Default	Description
values	list of 4 arrays	None	One array per quantile, each of length M×N
cube_data	DataFrame	None	Single-row DataFrame with columns Q{vel}_vel_Q{acc}_acc_Q{angle}_angle
M	int	5	Number of columns
N	int	5	Number of rows
minimum	float	data min rounded down to nearest 0.01	Colormap lower bound
maximum	float	data max rounded up to nearest 0.01	Colormap upper bound
cmap	str or Colormap	"Reds" (sequential data) / "RdBu_r" (diverging data with negative + positive values)	Matplotlib colormap
title	str	"Quantile Cube"	Plot title and default save filename
colorbar_label	str	""	Colorbar label
colorbar_ticks	list[float]	Matplotlib default	Colorbar tick labels
xlabel	str	"Velocity"	X-axis label
ylabel	str	"Acceleration"	Y-axis label
quantile_labels	list of 4 str	["Angle Q1","Angle Q2","Angle Q3","Angle Q4"]	Triangle labels
show_quantile_labels	bool	False	Show label-only summary view
show_values	bool	False	Print numeric value at center of each triangle
value_fmt	str	".4f"	Format string for numeric labels when show_values=True
grey_nonsignificant	bool	False	Render NaN values in grey
save	bool	False	Save figure to file
save_path	str	"<title>.png"	Custom save path
show	bool	True	Call plt.show()
figsize	tuple	(7, 7)	Figure size in inches

Advanced Usage

Custom axis labels

plot_cube(
    values=[q1, q2, q3, q4],
    xlabel="Speed Bins",
    ylabel="Acceleration Bins",
)

Custom quantile labels

plot_cube(
    values=[q1, q2, q3, q4],
    quantile_labels=["Low", "Mid-Low", "Mid-High", "High"],
    show_quantile_labels=True,
)

Custom colorbar ticks

plot_cube(
    values=[q1, q2, q3, q4],
    colorbar_ticks=[-0.2, -0.1, 0, 0.1, 0.2],
    colorbar_label="Effect Size"
)

Handling non-significant values

import numpy as np

q1_with_nans = np.where(pvalues > 0.05, np.nan, q1)

plot_cube(
    values=[q1_with_nans, q2, q3, q4],
    grey_nonsignificant=True,
)

Saving figures

plot_cube(
    values=[q1, q2, q3, q4],
    title="my_plot",
    save=True,
    save_path="outputs/my_plot.png",
    show=False,
)

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How It Works

Each cell in the grid corresponds to a (velocity, acceleration) quantile bin. Within each cell, four triangles represent four angle quantiles, encoding directional movement.

Color intensity reflects the value associated with each bin, typically representing relative density or normalized magnitude of observations within that velocity–acceleration–angle combination. This allows comparison of movement structure across all three dimensions simultaneously.

When data includes both positive and negative values, a diverging colormap centered at 0 is used to distinguish directionality (e.g., above/below baseline behavior). Missing or non-significant values (NaNs) can optionally be rendered in grey to indicate suppressed or unreliable estimates.

Tip: In density-based mode, values across all triangles sum to 1.0, meaning the colormap reflects relative time spent. In signed or effect-size mode, values represent magnitude and direction rather than proportions.

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Contributing

Contributions, bug reports, and feature requests are welcome!

1. Fork the repo: github.com/kelanethomas/quantile-cube
2. Create a branch: git checkout -b feature/your-feature
3. Commit your changes and open a pull request

Please open an issue first if you're planning a larger change.

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Citation

This package accompanies the following paper:

Thomas, K. & Hannig, J. (2025). Movement Dynamics in Elite Female Soccer Athletes: The Quantile Cube Approach. arXiv preprint arXiv:2503.11815. https://arxiv.org/abs/2503.11815

Accepted at the Journal of Quantitative Analysis in Sports — full publication coming soon.

@misc{thomas2025quantilecube_paper,
  author = {Thomas, Kendall and Hannig, Jan},
  title  = {Movement Dynamics in Elite Female Soccer Athletes: The Quantile Cube Approach},
  year   = {2025},
  eprint = {2503.11815},
  archivePrefix = {arXiv},
  url    = {https://arxiv.org/abs/2503.11815},
}

To also cite the software package:

@software{thomas2026quantilecube_pkg,
  author  = {Thomas, Kendall},
  title   = {quantile-cube: 3D Movement Distribution Visualization},
  year    = {2026},
  url     = {https://github.com/kelanethomas/quantile-cube},
  version = {0.1.3},
}

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License

MIT