Plotext Financial Chart Skill

Create ASCII financial line charts for GitHub Flavored Markdown using plotext with dot marker (• ). Pure text output — renders correctly on GitHub, terminals, and all monospace environments.

Analogy: graph-easy is for flowcharts. plotext with dot marker is for financial line charts.

When to Use This Skill

• Adding price path / line chart diagrams to markdown documentation

• Visualizing trading concepts (barriers, thresholds, entry/exit levels)

• Any GFM markdown file needing financial data visualization

• User mentions "financial chart", "line chart", "price chart", "plotext", or "trading chart"

NOT for: Flowcharts or architecture diagrams — use graph-easy for those.

Preflight Check

All-in-One Preflight Script

/usr/bin/env bash << 'PREFLIGHT_EOF' python3 --version &>/dev/null || { echo "ERROR: Python 3 not found"; exit 1; } if command -v uv &>/dev/null; then PM="uv pip" elif command -v pip3 &>/dev/null; then PM="pip3" else echo "ERROR: Neither uv nor pip3 found"; exit 1; fi python3 -c "import plotext" 2>/dev/null || { echo "Installing plotext via $PM..."; $PM install plotext; } python3 -c " import plotext as plt, re plt.clear_figure() plt.plot([1,2,3], [1,2,3], marker='dot') plt.plotsize(20, 5) plt.theme('clear') output = re.sub(r'\x1b[[0-9;]*m', '', plt.build()) assert '•' in output " && echo "✓ plotext ready (dot marker verified)" PREFLIGHT_EOF

Quick Start

import re import plotext as plt

x = list(range(20)) y = [97, 98, 100, 101, 100, 98, 100, 101, 102, 101, 100, 98, 100, 101, 102, 103, 102, 101, 100, 100]

plt.clear_figure() plt.plot(x, y, marker="dot", label="Price path") plt.hline(103) # Upper barrier plt.hline(97) # Lower barrier plt.hline(100) # Entry price plt.title("Triple Barrier Method") plt.xlabel("Time (bars)") plt.ylabel("Price") plt.plotsize(65, 22) plt.theme("clear") print(re.sub(r'\x1b[[0-9;]*m', '', plt.build()))

Mandatory Settings

Every chart MUST use these settings:

Setting Code Why

Reset state plt.clear_figure()

Prevent stale data

Dot marker marker="dot"

GitHub-safe alignment

No color plt.theme("clear")

Clean text output

Strip ANSI re.sub(r'\x1b[…', '', …)

Remove residual escape codes

Build as string plt.build()

Not plt.show()

Marker Reference

Marker GitHub Safe Use When

"dot"

Yes Default — always use

"hd"

Yes Terminal-only, need smoothness

"braille"

No Never for markdown

"fhd"

No Never — Unicode 13.0+ only

Rendering Command

/usr/bin/env bash << 'RENDER_EOF' python3 << 'CHART_EOF' import re import plotext as plt

x = list(range(20)) y = [97, 98, 100, 101, 100, 98, 100, 101, 102, 101, 100, 98, 100, 101, 102, 103, 102, 101, 100, 100]

plt.clear_figure() plt.plot(x, y, marker="dot", label="Price path") plt.hline(103) plt.hline(97) plt.hline(100) plt.title("Triple Barrier Method") plt.xlabel("Time (bars)") plt.ylabel("Price") plt.plotsize(65, 22) plt.theme("clear") print(re.sub(r'\x1b[[0-9;]*m', '', plt.build())) CHART_EOF RENDER_EOF

Embedding in Markdown (MANDATORY: Source Adjacent to Chart)

Every chart MUST be immediately followed by a <details> block with Python source. Explanatory text goes after the <details> block, never between chart and source.

✅ CORRECT: Chart → <details> → Explanatory text ❌ WRONG: Chart → Explanatory text → <details>

See ./references/api-and-patterns.md for full embedding template.

Mandatory Checklist

• plt.clear_figure() — Reset state

• marker="dot" — Dot marker for GitHub

• plt.theme("clear")

• re.sub() strip — No ANSI codes

• plt.title("...") — Every chart needs a title

• plt.xlabel / plt.ylabel — Axis labels

• plt.plotsize(65, 22) — Fits 80-col code blocks

• <details> block immediately after chart (before any explanatory text)

Troubleshooting

Issue Cause Solution

ANSI codes in output Missing theme/strip Add plt.theme("clear") and re.sub() strip

Misaligned on GitHub Wrong marker type Use marker="dot" , never braille/fhd

Chart too wide plotsize too large Use plt.plotsize(65, 22) for 80-col blocks

No diagonal slopes Too few data points Use 15+ data points for visible slopes

ModuleNotFoundError

Not installed Run preflight check

Empty output Missing build()

Use plt.build() not plt.show()

Resources

• plotext GitHub

• Full API, patterns, and embedding guide

• Tool selection rationale