mplstereonet

mplstereonet is a skill for Claude Code, Codex from SteadfastAsArt/geoscience-skills. It costs 113 tokens per session (1,789 once invoked), scanned A, original, MIT.

A Matplotlib extension for stereonet plots, which show three-dimensional geological orientations on a two-dimensional circular diagram. It can display planes, poles, and lineations such as the direction of a geological feature.

In plain words
What is it for?
Use it to plot planes and their poles, show lineations, create density contours, and calculate best-fit or average orientations.
Why use it?
It makes orientation measurements easier to compare, summarize, and inspect visually.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to plot planes and their poles, show lineations, create density contours, and calculate best-fit or average orientations.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/steadfastasart/geoscience-skills/mplstereonet
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add SteadfastAsArt/geoscience-skills --skill mplstereonet
Clone the repo
git clone --depth 1 https://github.com/SteadfastAsArt/geoscience-skills

Made for: Claude Code, Codex.

Its marketplace also offers this one on its own, as the plugin mplstereonet/plugin install mplstereonet after adding the marketplace above.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for mplstereonet

README.md
[![agentmods](https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/mplstereonet/github.svg)](https://agentmods.dev/skills/steadfastasart/geoscience-skills/mplstereonet)
Your own site
<a href="https://agentmods.dev/skills/steadfastasart/geoscience-skills/mplstereonet"><img src="https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/mplstereonet/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for mplstereonet

Your own site · 80×15
<a href="https://agentmods.dev/skills/steadfastasart/geoscience-skills/mplstereonet"><img src="https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/mplstereonet.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 113 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,789 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00113 $0.01789
Opus 5 $0.00056 $0.00894
Sonnet 5 $0.00023 $0.00358
Haiku 4.5 $0.00011 $0.00179

Measured 12d ago against content hash a0ee23ba4f2d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

mplstereonet scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/structural_analysis.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

mplstereonet/SKILL.md · 194 lines

How it starts

The opening of the file, as written. The whole thing — 194 lines — stays where its author put it; the contents beside it link to each section on GitHub.

mplstereonet - Stereonets for Matplotlib

Quick Reference

import mplstereonet
import matplotlib.pyplot as plt

# Create stereonet
fig, ax = mplstereonet.subplots()

# Plot plane and pole (strike/dip, right-hand rule)
ax.plane(315, 45, 'b-')          # Great circle
ax.pole(315, 45, 'ko')           # Pole to plane

# Plot lineation (trend/plunge)
ax.line(120, 30, 'r^')

ax.grid()
plt.savefig('stereonet.png', dpi=150)

Key Functions

Function Purpose
mplstereonet.subplots() Create stereonet figure and axes
ax.plane(strike, dip) Plot great circle
ax.pole(strike, dip) Plot pole to plane
ax.line(trend, plunge) Plot lineation point
ax.density_contourf() Filled density contours
mplstereonet.fit_girdle() Best-fit great circle
mplstereonet.find_mean_vector() Mean orientation

Essential Operations

Multiple Measurements with Contours

import numpy as np

strikes = [45, 52, 38, 48, 55, 41, 50, 43]
dips = [25, 30, 22, 28, 35, 24, 32, 27]

fig, ax = mplstereonet.subplots()

# Density contour of poles
ax.density_contourf(strikes, dips, measurement='poles', cmap='Reds')
ax.pole(strikes, dips, 'k.', markersize=5)

ax.grid()
ax.set_title('Bedding Orientations')
plt.savefig('density.png', dpi=150)

Calculate Mean Orientation

# Fit best-fit plane (girdle)
mean_strike, mean_dip = mplstereonet.fit_girdle(strikes, dips)

# Or calculate mean pole for clustered data
lon, lat = mplstereonet.pole(strikes, dips)
mean_lon, mean_lat = mplstereonet.find_mean_vector(lon, lat)
mean_s, mean_d = mplstereonet.pole2strike(mean_lon, mean_lat)

Pi-Diagram (Fold Axis)

# Bedding measurements around a fold
strikes = np.array([20, 35, 50, 70, 90, 110, 130, 150, 165, 180])
dips = np.array([45, 40, 35, 30, 25, 30, 35, 40, 45, 50])

fig, ax = mplstereonet.subplots()
ax.pole(strikes, dips, 'ko', markersize=6)

# Fit girdle to poles - fold axis is pole to girdle
girdle_strike, girdle_dip = mplstereonet.fit_girdle(strikes, dips)
ax.plane(girdle_strike, girdle_dip, 'r-', linewidth=2)

fold_trend, fold_plunge = mplstereonet.pole(girdle_strike, girdle_dip)
ax.line(fold_trend, fold_plunge, 'r^', markersize=12, label='Fold axis')

ax.grid()
ax.legend()

Read the full file on GitHub · 194 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 194 lines · 113 tokens per session scan A a0ee23ba4f2d

Subscribe to this mod's changes

mplstereonet is a skill published in the GitHub repository SteadfastAsArt/geoscience-skills (59 stars, last pushed 5mo ago), licensed MIT. It adds 113 tokens to every session and 1,789 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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