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: vector or matrix.

• levels - Contour levels: scalar or vector.

• LineSpec - Line style and color

• ax - a scalar graphics object value: parent container, specified as a 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 the contour lines to display 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 the 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, ensuring comprehensive coverage of the data range. 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: scalar in range [0, 1] or 1 (default).
LineStyle	Line style: '--', ':', '-.' or '-' (default).
LineWidth	Line Width: positive value or 0.5 (default).
ContourMatrix	contour matrix.
XData	x values: vector or matrix or [] (default).
YData	y values: vector or matrix or [] (default).
ZData	z values: vector or 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.
HandleVisibility	Visibility of handle 'on', 'off'.
Type	Type of graphics object '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 object is created. Set this property on an existing component has no effect.
DeleteFcn	Callback (function handle, string or cell) called when 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)

🔗 See also

contour3, surf, mesh.

🕔 History

Version	📄 Description
1.3.0	initial version
1.7.0	CreateFcn, DeleteFcn callback added.
--	BeingDeleted property added.