Matlab Build Chart

MATLAB Chart Builder

Create, customize, and interact with MATLAB charts and plots — in standalone figures, Live Scripts, or uifigure apps.

When to Use This Skill

Use this skill when:

• Plotting data (line, scatter, bar, histogram, heatmap, surface, polar, geo, volume) in any context
• Configuring axes (labels, limits, ticks, legend, font, export)
• Adding annotations (xline, yline, xregion, text)
• Adding or customizing data tips
• Creating interactive plots (click, hover, drag callbacks)
• Animating or streaming data to a chart
• Arranging multiple axes with tiledlayout/nexttile
• Optimizing chart rendering performance
• Exporting figures for publication or reports
• User says "help me visualize this" without a specific chart type

When NOT to Use This Skill

• Building a full app (use matlab-build-app — it invokes this skill for chart sub-steps)
• Applying dark mode, brand colors, or custom color themes (use matlab-apply-theme)
• Working with Simulink scopes or Simscape plots
• Creating App Designer charts via the drag-and-drop GUI

Workflow

User request arrives
        |
        +-- FAST PATH (most requests)
        |   Chart type named OR unambiguous single-axes plot
        |   AND no interactivity / animation / multi-panel / performance concern
        |       |
        |       v
        |   Infer rendering context (default: standalone figure)
        |   Read relevant references --> Build directly
        |
        +-- PLAN PATH (complex or ambiguous)
                |
                +-- Ambiguous intent (no chart type named, unclear data question)
                |       --> Identify visualization intent (see Intent Taxonomy)
                |
                +-- Rendering context unclear AND it matters
                |       --> Ask: standalone figure, Live Script, or uifigure app?
                |
                v
            Present inline plan for approval
                |
                v
            User confirms --> Read references --> Build

Fast-Path Triggers (build directly, no plan)

ALL of these must hold:

• Chart type is named OR intent maps unambiguously to one type
• Single axes (no tiled/multi-panel layout)
• No custom interactivity (no user-specified callbacks)
• No animation or streaming
• No explicit performance constraints
• Rendering context is clear or defaults to standalone figure

Plan-Path Triggers (present plan first)

ANY of these fires the plan path:

• Multi-panel / tiled figure
• Custom interactivity (click, hover, drag callbacks)
• Animation or streaming data
• Performance-sensitive (large dataset, real-time update)
• Branded / designed figure requiring palette/theme coordination
• Ambiguous "help me visualize this" — unclear type or intent
• Multiple visualization intents in one figure

Rendering Context

Three contexts gate which constraint set applies:

If context is unstated and cannot be inferred, assume standalone figure. Ask only when the distinction matters (e.g., heatmap parent differs between contexts).

Visualization Intent Taxonomy

Engages ONLY when the user has NOT named a specific chart type or function. If they say "scatter" or "heatmap," skip intent selection and build directly.

Communicative Intents

Data-Domain Intents

Classification Rules

• The waterfall trap: MATLAB's waterfall is a 3D surface plot, NOT the financial accumulation chart. For "accumulation to total," build from bar with a hidden base series.
• f* variants follow their data counterpart's intent: fplot -> Trend, fsurf/fmesh/fcontour -> Surfaces, fimplicit -> Relationship, fpolarplot -> Directional.
• Animation is cross-cutting, not an intent. animatedline, comet, comet3 layer motion onto any chart type. See references/animation.md.
• Multi-intent functions: Classify by the user's data question, not gallery grouping. E.g., heatmap of a correlation matrix -> Relationship; heatmap of counts -> Comparison.
• Classify by communicative intent, not MATLAB docs grouping. piechart/donutchart are Composition regardless of where docs file them.

Inline Plan Template

When the plan path engages, present for approval:

**Chart Plan: [description]**

**Context:** [Standalone figure / Live Script / uifigure app]
**Intent:** [name] -> [chosen function(s)]

**Structure:**
- [Layout description]
- [Key visual elements, annotations, interactions]

**Key decisions:**
- [Performance strategy, if applicable]  [src: references/performance.md SS]
- [Interaction model, if applicable]  [src: references/interactive-plots.md SS]
- [uifigure constraints that apply, if context = uifigure]

**References to use:**
| Reference | Role | Provenance |
|-----------|------|------------|
| `references/file.md` | [what it provides] | [src: references/file.md SS] |

Shall I proceed?

Do NOT write the plan to a file unless (a) the user explicitly asks for a spec to keep, or (b) chart-builder is running as a sub-step of an app build with an existing plan artifact.

Critical Rules

Universal (all contexts)

• MUST pass axes as first argument to all plotting functions: plot(ax, x, y) not plot(x, y)
• MUST update data in place (p.XData = newX) — never replot in a loop
• MUST use drawnow limitrate for animations — never bare drawnow in tight loops
• PREFER tiledlayout/nexttile over subplot() for multiple axes
• PREFER exportgraphics() for publication-quality export

Additional constraints in uifigure apps

• MUST use uiaxes — never plain axes
• MUST use exportgraphics() or exportapp() — saveas/print not supported
• NEVER use subplot() — not supported in uifigure
• NEVER use annotation() — use text(), xline(), yline(), xregion(), yregion()
• NEVER use ginput() — use ButtonDownFcn on plot objects
• NEVER rely on gcf/gca — uiaxes has HandleVisibility = 'off' by default

Quick Start

Standalone figure

fig = figure;
ax = axes(fig);

t = 0:0.01:2*pi;
plot(ax, t, sin(t), 'LineWidth', 1.5);
hold(ax, 'on');
plot(ax, t, cos(t), '--', 'LineWidth', 1.5);
hold(ax, 'off');

title(ax, 'Sine and Cosine');
xlabel(ax, 'Time (s)');
ylabel(ax, 'Amplitude');
legend(ax, 'sin', 'cos');
grid(ax, 'on');
exportgraphics(ax, 'plot.png', 'Resolution', 300);

In a uifigure app

fig = uifigure('Name', 'Chart Demo');
gl = uigridlayout(fig, [1 1]);
ax = uiaxes(gl);

plot(ax, t, sin(t), 'LineWidth', 1.5);
% Same API from here — only axes creation differs

Once you have ax, all plotting calls (plot, scatter, bar, xline, hold, legend, colororder, etc.) are identical regardless of context.

Implementation Checklist

Graphics

• All plot calls pass ax as first argument
• hold(ax, 'on') used before adding multiple series
• Axes labels, title, and grid configured
• Annotations use xline/yline/text (not annotation() — uifigure requirement)
• Interactive callbacks use ButtonDownFcn on plot objects (not axes — uifigure requirement)
• Animations use drawnow limitrate and pre-set axis limits
• Export uses exportgraphics() (required in uifigure; preferred everywhere)
• Multiple axes use tiledlayout/nexttile (required in uifigure; preferred everywhere)

Troubleshooting

Issues marked (uifigure only) apply only when plotting in uifigure apps.

References

Reference Gaps (follow-up authoring needed)

These intents have no dedicated reference file. Use built-in MATLAB API knowledge:

• Composition — piechart, donutchart, stacked bar/area, wordcloud, bubblecloud
• Geospatial — geoplot, geoscatter, geobubble, geodensityplot
• Directional / polar — polarplot, polarscatter, polarhistogram, polarbubblechart, compassplot, fpolarplot
• Vector fields & flow — quiver, quiver3, feather, streamline, streamslice, streamribbon, streamtube, streamparticles, coneplot
• Volume visualization — slice, contourslice, coneplot, isosurface/isocap workflows
• Images & matrices (partial) — image, imagesc not covered; heatmap in plot-types
• Surfaces (partial) — only surf covered; mesh, contour, ribbon, pcolor pending

External Skills (invoked, not read)

• matlab-apply-theme — when the chart needs dark mode, brand colors, or custom palettes

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