Geom.contour

Draw contours of a 2D function or a matrix.

Aesthetics

z: 2D function or a matrix that represent "heights" relative to to the x-y plane.
x (optional): Vector of X-coordinates. If z is a matrix, then the length of x must be equal to the number of rows in z.
y (optional): Vector of Y-coordinates. If z is a matrix, then the length of y must be equal to the number of columns in z.

levels (optional): Sets the number of contours to draw, defaults to 15. It takes either a vector of contour levels; an integer that specifies the number of contours to draw; or a function which inputs z and outputs either a vector or an integer.

plot(z=(x,y) -> x*exp(-(x-round(Int, x))^2-y^2),
     x=linspace(-8,8,150), y=linspace(-2,2,150), Geom.contour)

volcano = float(array(dataset("datasets", "volcano")))
plot(z=volcano, Geom.contour)

plot(z=volcano, Geom.contour(levels=[110.0, 150.0, 180.0, 190.0]))

plot(z=volcano, x=collect(0.0:10:860.0), y=collect(0.0:10:600.0),
     Geom.contour(levels=2))