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:

Context	Constraints	How inferred
Standalone figure	Universal rules only	Default; `figure`/`axes` in request
Live Script	Universal rules only	User mentions Live Script, `.mlx`, plain-text Live Code
uifigure app	Universal + uifigure rules	User mentions uifigure; arrives as sub-step of app-builder

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

Intent	Data question	Encouraged functions
Comparison	How do values compare across items?	`bar`, `barh`, `bar3`, `bar3h`, `pareto`, `stem`, `stairs`, `loglog`, `semilogx`, `semilogy`
Trend / time series	How does a value change over time?	`plot`, `area`, `stackedplot`, `stairs`, `stem`, `fplot`, `fplot3`
Distribution	How is data spread?	`histogram`, `histogram2`, `boxchart`, `violinplot`, `raincloudplot`, `swarmchart`, `swarmchart3`, `scatterhistogram`, `binscatter`, `polarhistogram`
Relationship	How do variables relate?	`scatter`, `scatter3`, `bubblechart`, `bubblechart3`, `plotmatrix`, `parallelplot`, `binscatter`, `spy`, `fimplicit`
Composition	Parts of a whole?	`piechart`, `donutchart`, stacked `bar`, stacked `area`, `wordcloud`, `bubblecloud`

Data-Domain Intents

Intent	When it fires	Encouraged functions
Geospatial	Geographic coordinates	`geoplot`, `geoscatter`, `geobubble`, `geodensityplot`
Directional / polar	Angular, cyclical, compass data	`polarplot`, `polarscatter`, `polarhistogram`, `polarbubblechart`, `compassplot`, `fpolarplot`
Surfaces & scalar fields	z = f(x,y), meshes, contours	`surf`, `surfc`, `surfl`, `mesh`, `meshc`, `meshz`, `ribbon`, `pcolor`, `contour`, `contourf`, `contour3`, `fcontour`, `fsurf`, `fmesh`, `fimplicit3`, `waterfall`
Vector fields & flow	Directional vector data	`quiver`, `quiver3`, `feather`, `streamline`, `streamslice`, `streamribbon`, `streamtube`, `streamparticles`, `coneplot`
Volume visualization	3D gridded volume data	`slice`, `contourslice`, `coneplot`, `streamslice`, isosurface/isocap workflows
Images & matrices	Display a matrix/grid	`image`, `imagesc`, `heatmap`, `pcolor` (flat), `spy`

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.

Problem	Cause	Fix
Animation is slow/jerky	Using `plot()` in loop or bare `drawnow`	Update data in place + `drawnow limitrate`
Plot disappears after replot	Default `NextPlot = 'replacechildren'`	Use `hold(ax, 'on')` or update data in place
`gcf`/`gca` return wrong handle (uifigure only)	uiaxes `HandleVisibility = 'off'`	Always pass `ax` explicitly
`annotation()` error (uifigure only)	Not supported in uifigure	Use `text()`, `xline()`, `yline()`
`ginput()` error (uifigure only)	Not supported in uifigure	Use `ButtonDownFcn` on plot objects
Click callback doesn't fire on axes (uifigure only)	`ButtonDownFcn` unreliable on uiaxes	Put `ButtonDownFcn` on plot objects
Heatmap fails in uiaxes (uifigure only)	Heatmap needs figure/panel parent	Use `heatmap(fig, ...)` or `heatmap(panel, ...)`
`saveas` fails (uifigure only)	Not supported for uifigure	Use `exportgraphics(ax, file)`
`subplot()` errors (uifigure only)	Not supported in uifigure	Use `tiledlayout`/`nexttile` or `uigridlayout`

References

Topic	File	Coverage	Intent served
Plot types	`references/plot-types.md`	Line, scatter, bar, histogram, heatmap, surface	Comparison, Trend, Distribution, Relationship, Surfaces (partial)
Axes configuration	`references/axes-config.md`	uiaxes setup, labels, limits, ticks, font, legend, export	All intents
Annotations	`references/annotations.md`	xline, yline, xregion, text, patch	All intents (overlay)
Data tips	`references/data-tips.md`	DataTipTemplate, custom rows, programmatic tips	All intents (overlay)
Interactive plots	`references/interactive-plots.md`	ButtonDownFcn, mouse callbacks, drag, HitTest, toolbar	Plan-path: interactivity
Chart palettes	`references/chart-palettes.md`	colororder, named palettes, SeriesIndex, vs colormap	All intents (styling)
Animation	`references/animation.md`	Update in place, animatedline, streaming, performance	Plan-path: animation
Multiple axes	`references/multiple-axes.md`	tiledlayout, nexttile, linkaxes, peripheral tiles	Plan-path: multi-panel
Performance	`references/performance.md`	Lazy-load, batch updates, throttle, parfeval, startup	Plan-path: performance

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