# Matplotlib Charts

> Produce PNG charts with matplotlib. Save to chart-<slug>.png in the working directory.

- Skill: `jin-bo/matplotlib-charts` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jin-bo/matplotlib-charts`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jin-bo/matplotlib-charts/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jin-bo (https://skillmd.com/u/jin-bo)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/jin-bo/matplotlib-charts

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# Matplotlib Charts

## Format

- One chart per question. No subplots unless the user asks.
- `figsize=(10, 6)`; keep labels readable.
- Save as PNG with `plt.savefig(path, dpi=120, bbox_inches="tight")`.
- Do not call `plt.show()` — the environment is headless (`MPLBACKEND=Agg`).

## Style

- Default matplotlib style is fine; avoid exotic third-party themes.
- Set a clear title, x/y labels, and rotate x ticks if labels overlap.

## Return contract

After saving the chart, your FINAL assistant message must include **exactly one** line:

`[CHART] chart-<slug>.png`

The host UI parses this marker to render the image. Do not wrap it in code fences, backticks, or quotes.

## Example

```python
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt

fig, ax = plt.subplots(figsize=(10, 6))
ax.bar(products, revenues)
ax.set_title("Revenue by product")
ax.set_ylabel("Revenue ($)")
plt.savefig("chart-revenue.png", dpi=120, bbox_inches="tight")
```

Then end your reply with:

`[CHART] chart-revenue.png`