Advanced Plotting

Earlier in the class we saw how to create basic line and scatter plots.
MATLAB can also plot 3-d surfaces, bar and pie charts, etc.

To make a 3d plot of a set of (x,y,z) data points, call:
plot3(x,y,z,LineSpec)

LineSpec is optional, same options as a regular plot command


Often want to visualize a surface of the form z = f(x,y)
Need the equivalent of many closely spaced x-values we used when plotting in 2-d
[X, Y] = meshgrid(x,y) - creates a 2-d rectangular grid with x coordinates
defined by x and y coordinates defined by y

Can visualize this using scatter (creates a scatter plot)

Contour plot - Visualizes 3-d info in 2-d
Each contour has the same function value at each point

contour(X,Y,Z) or contour(X,Y,Z,n)
X and Y are the coordinates from meshgrid. Z is the function values at those points.
If n is set, it defines the number of contours to be plotted.

Why is this a reasonable visualization? Show standard quadratic plot without line connecting points

contour3(X,Y,Z) or contour3(X,Y,Z,n)
Same as contour but contours are drawn at cooresponding Z level


mesh(X, Y, Z)
Creates a "wire frame", color helps illustrate the function value

surf(X, Y, Z)
Creates a 3-d surface plot

subplot(rows, cols, loc) - creates rows-by-cols matrix of plot areas and makes loc the current one

meshc – combination mesh/contour plot
meshz – 3-D mesh with curtain
surfc – combination surface/contour plot

Bar plots
bar - standard bar plot
barh - horizontal bar plot
bar3 - 3d bar plot

Histograms
hist(X, N) – histogram for elements of X into N bins, or N = vec of bin center values

Pie Charts
pie(X) – pie chart of data in X, values are normalized via X/sum(X), can "explode" pieces
pie3(X) – 3-D pie chart