contour

Contour plot of matrix

📝Syntax

contour(Z)
contour(X, Y, Z)
contour(..., levels)
contour(..., LineSpec)
contour(ax, ...)
M = contour(...)
[M, h] = contour(...)

📥Input Arguments

Parameter	Description
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 Arguments

Parameter	Description
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

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);

rng('default');
f = figure();
N = 50;
contour(1:N, 1:N, rand(N), 5)

f = figure();
Z = peaks;
Z(:, 26) = NaN;
contour(Z)

Labeled contour lines.

[X, Y, Z] = peaks;

[C, h] = contour(X, Y, Z);

clabel(C, h);

🕔Version History

Version	Description
1.3.0	Initial version.
1.7.0	CreateFcn and DeleteFcn callbacks added.
1.8.0	BeingDeleted property added.

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