> For the complete documentation index, see [llms.txt](https://nelson-9.gitbook.io/nelson/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nelson-9.gitbook.io/nelson/markdown/en/graphics/contour.md). # contour Contour plot of matrix ## 📝 Syntax * contour(Z) * contour(X, Y, Z) * contour(..., levels) * contour(..., LineSpec) * contour(ax, ...) * M = contour(...) * \[M, h] = contour(...) ## 📥 Input argument * X - x-coordinates: vector or matrix. * Y - y-coordinates: vector or matrix. * Z - z-coordinates: matrix. * levels - Contour levels: scalar or vector. * LineSpec - Line specification defining line style and color. * ax - a scalar graphics object value: parent container specified as an axes. ## 📤 Output argument * M - Contour matrix. * h - a graphics object: contour type. ## 📄 Description contour(Z) generates a contour plot representing isolines of the matrix Z. Each isoline corresponds to a specific height value on the x-y plane. Nelson automatically selects contour lines based on the values in Z. The column and row indices of Z serve as the x and y coordinates in the plane, respectively. contour(X, Y, Z) allows the user to specify the x and y coordinates corresponding to the values in matrix Z. This enables more precise control over the positioning of the contour plot on the x-y plane. The matrices X and Y provide the coordinates, while Z contains the height values for generating the contour plot. Property Name-Value Pairs: | Property | Description | | -------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **LevelList** | The contour levels, specified as a vector of z values, determine the height levels at which contour lines are drawn. By default, when not explicitly provided, the contour function automatically selects these values to cover the range of values present in the ZData property. Default: empty matrix. | | **LevelListMode** | Selection mode for LevelList: 'manual' or 'auto' (default). | | **LevelStep** | Spacing between contour lines: scalar numeric value or 0 (default). | | **LevelStepMode** | Selection mode for LevelStep: 'manual' or 'auto' (default). | | **EdgeColor** | Color of contour lines: rgb color or 'flat' (default). | | **EdgeAlpha** | Contour line transparency specified as a scalar in the range \[0, 1]. Default: 1. | | **LineStyle** | Line style: '--', ':', '-.' or '-' (default). | | **LineWidth** | Line width: positive numeric scalar. Default: 0.5. | | **ContourMatrix** | Contour matrix returned by contourc. | | **XData** | x values: vector or matrix or \[] (default). | | **YData** | y values: vector or matrix or \[] (default). | | **ZData** | z values: matrix or \[] (default). | | **XDataMode** | Selection mode for XData: 'manual' or 'auto' (default). | | **YDataMode** | Selection mode for YData: 'manual' or 'auto' (default). | | **DisplayName** | Legend label: character vector, string scalar or ' '(default). | | **Visible** | State of visibility: on/off logical value, 'on' (default). | | **Parent** | Parent: Axes object or Group object. | | **Children** | Children graphics objects. | | **HandleVisibility** | Visibility of handle: 'on' or 'off'. | | **Type** | Object type: 'contour'. | | **Tag** | Object identifier: character vector, string scalar or ' ' (default). | | **UserData** | User data: array or \[] (default). | | **CreateFcn** | Callback (function handle, string or cell) called when the object is created. Setting this property on an existing component has no effect. | | **DeleteFcn** | Callback (function handle, string or cell) called when the object is deleted. | | **BeingDeleted** | Flag indicating that the object is being deleted. | ## 💡 Examples ```matlab f = figure(); subplot(2, 3, 1) x = linspace(-2 * pi, 2 * pi); y = linspace(0, 4 * pi); [X, Y] = meshgrid(x, y); Z = sin(X) + cos(Y); contour(X, Y, Z); subplot(2, 3, 2) [X, Y, Z] = peaks; contour(X, Y, Z, 20) subplot(2, 3, 3) [X, Y, Z] = peaks; v = [1, 1]; contour(X, Y, Z, v) subplot(2, 3, 4) [X, Y, Z] = peaks; contour(X, Y, Z, '-.') subplot(2, 3, 5) Z = peaks; [M, c] = contour(Z); c.LineWidth = 3; subplot(2, 3, 6) [theta, r] = meshgrid(linspace(0, 2 * pi, 64), linspace(0, 1, 64)); [X, Y] = pol2cart(theta, r); Z = sin(2 * theta) .* (1 - r); contour(X, Y, abs(Z), 10); ``` ![](/files/AZpqdEMyRBRHpG2lS89v) ```matlab rng('default'); f = figure(); N = 50; contour(1:N, 1:N, rand(N), 5) ``` ![](/files/nvzE1SE0LtyPeyRa4RAf) ```matlab f = figure(); Z = peaks; Z(:, 26) = NaN; contour(Z) ``` ![](/files/kWuttxmlyFEDTPDBN4sF) Labeled contour lines. ```matlab [X, Y, Z] = peaks; [C, h] = contour(X, Y, Z); clabel(C, h); ``` ## 🔗 See also [contourc](/nelson/markdown/en/graphics/contourc.md), [contourf](/nelson/markdown/en/graphics/contourf.md), [contour3](/nelson/markdown/en/graphics/contour3.md), [clabel](/nelson/markdown/en/graphics/clabel.md), [surf](/nelson/markdown/en/graphics/surf.md), [mesh](/nelson/markdown/en/graphics/mesh.md). ## 🕔 History | Version | 📄 Description | | ------- | ---------------------------------------- | | 1.3.0 | Initial version. | | 1.7.0 | CreateFcn and DeleteFcn callbacks added. | | 1.8.0 | BeingDeleted property added. | --- # Agent Instructions This documentation is published with GitBook. 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