{
"title": "contourf",
"category": "plotting",
"keywords": [
"contourf",
"filled contour plot",
"level regions",
"scalar field heatmap",
"matlab contourf"
],
"summary": "Create filled contour plots for level regions, scalar fields, and MATLAB `contourf` workflows.",
"hero_image": "https://web.runmatstatic.com/builtin-image/runmat-matlab-plot-contourf-interference-pattern.webp",
"gpu_support": {
"elementwise": false,
"reduction": false,
"precisions": [
"single",
"double"
],
"broadcasting": "none",
"notes": "`contourf` uses the shared filled-contour pipeline and returns a contour-fill handle."
},
"fusion": {
"elementwise": false,
"reduction": false,
"max_inputs": 3,
"constants": "inline"
},
"requires_feature": null,
"tested": {
"unit": "builtins::plotting::contourf::tests"
},
"description": "`contourf` creates filled contour plots by coloring the regions between contour levels. In RunMat it returns a contour-fill handle, shares the contour level-generation path with `contour`, and acts as the filled-region counterpart to line-oriented contour plots.",
"behaviors": [
"`contourf(Z)` uses implicit axes, while `contourf(X, Y, Z)` accepts explicit coordinates.",
"The returned value is a contour-fill handle in the plotting object system.",
"Level-list, level-count, and related contour workflows mirror the broader contour family semantics.",
"`contourf` works naturally with `colorbar` and `colormap` because filled regions are fundamentally color-mapped scalar ranges.",
"Filled contours and optional line overlays are handled through the shared contour stack."
],
"examples": [
{
"description": "Create a filled contour plot",
"input": "[X, Y] = meshgrid(-2:0.25:2, -2:0.25:2);\nZ = X .* exp(-X.^2 - Y.^2);\ncontourf(X, Y, Z);\ncolorbar;"
},
{
"description": "Use explicit levels with a colormap",
"input": "[X, Y] = meshgrid(-3:0.2:3, -3:0.2:3);\nZ = cos(X) .* sin(Y);\ncontourf(X, Y, Z, [-0.75 -0.25 0 0.25 0.75]);\ncolormap('turbo');"
},
{
"description": "Inspect the returned contour-fill handle",
"input": "[X, Y] = meshgrid(1:20, 1:20);\nZ = X - Y;\nh = contourf(X, Y, Z);\nget(h, 'Type')",
"output": "ans =\n 'contour'"
},
{
"description": "Filled scalar field with explicit levels",
"input": "[X, Y] = meshgrid(linspace(-3, 3, 150), linspace(-3, 3, 150));\nZ = sin(X) .* cos(Y) + 0.5*sin(2*X + Y);\n\ncontourf(X, Y, Z, 25);\ncolormap('turbo');\ncolorbar;\ntitle('Interference Pattern — Filled Contours');\nxlabel('x');\nylabel('y');\naxis equal;",
"image_webp": "https://web.runmatstatic.com/builtin-image/runmat-matlab-plot-contourf-interference-pattern.webp"
}
],
"faqs": [
{
"question": "What's the difference between contourf and contour?",
"answer": "`contourf` fills the regions between contour levels with solid colors from the colormap. `contour` draws only the boundary lines. If you're building a heatmap-style visualization where color bands carry meaning, `contourf` is the right choice. If you just need iso-lines overlaid on something else, use `contour`."
},
{
"question": "How does the colormap interact with contourf?",
"answer": "Each filled region maps to a range in the active colormap based on its contour level. Calling `colormap('hot')` after `contourf` recolors all regions immediately. Pair it with `colorbar` to show the value-to-color mapping.\n\n```matlab\ncontourf(X, Y, Z, 15);\ncolormap('hot');\ncolorbar;\n```"
},
{
"question": "How do I control the number of filled levels?",
"answer": "Pass an integer as the fourth argument to set the level count: `contourf(X, Y, Z, 20)` creates 20 levels. For exact control, pass a vector of level values instead: `contourf(X, Y, Z, [-1 -0.5 0 0.5 1])`. More levels give smoother color transitions but add rendering cost on large grids."
}
],
"links": [
{
"label": "contour",
"url": "./contour"
},
{
"label": "colorbar",
"url": "./colorbar"
},
{
"label": "colormap",
"url": "./colormap"
},
{
"label": "surfc",
"url": "./surfc"
},
{
"label": "meshc",
"url": "./meshc"
},
{
"label": "Choosing the right plot type",
"url": "/docs/plotting/choosing-the-right-plot-type"
},
{
"label": "Styling plots and axes",
"url": "/docs/plotting/styling-plots-and-axes"
},
{
"label": "Plot replay and export",
"url": "/docs/plotting/plot-replay-and-export"
},
{
"label": "Complete plotting guide",
"url": "/blog/matlab-plotting-guide"
}
],
"source": {
"label": "`crates/runmat-runtime/src/builtins/plotting/ops/contourf.rs`",
"url": "https://github.com/runmat-org/runmat/blob/main/crates/runmat-runtime/src/builtins/plotting/ops/contourf.rs"
}
}