Plotting and Visualization

## Learning Objectives - Create 2D plots - Customize plot appearance - Create 3D plots - Export and save figures ## Basic 2D Plotting ### Simple Line Plot ```matlab x = 0:0.1:2*pi; y = sin(x); plot(x, y) ``` ### Multiple Lines ```matlab x = 0:0.1:2*pi; plot(x, sin(x)) hold on plot(x, cos(x)) hold off ``` ### Plotting Functions ```matlab fplot(@(x) sin(x), [0, 2*pi]) fplot(@(x) x^2 - 2*x + 1, [-5, 5]) ``` ## Plot Customization ### Line Properties ```matlab x = 0:0.1:2*pi; y = sin(x); plot(x, y, 'r-', 'LineWidth', 2) % Red, solid, 2pt width ``` ### Color, Marker, Line Style | Code | Property | Code | Property | Code | Property | Code | Property | |------|----------|------|----------|------|----------|------|----------| | `b` | Blue | `g` | Green | `r` | Red | `c` | Cyan | | `m` | Magenta | `y` | Yellow | `k` | Black | `w` | White | | `-` | Solid | `--` | Dashed | `:` | Dotted | `-.` | Dash-dot | | `.` | Point | `o` | Circle | `x` | X-mark | `+` | Plus | | `*` | Star | `s` | Square | `d` | Diamond | `^` | Triangle | ### Markers ```matlab plot(x, y, 'ro-') % Red circles with line plot(x, y, 'b--') % Blue dashed plot(x, y, 'gs') % Green squares ``` ## Axis and Labels ### Axis Labels ```matlab x = 0:0.1:2*pi; y = sin(x); plot(x, y) xlabel('x (radians)') ylabel('sin(x)') title('Sine Function') ``` ### Axis Limits ```matlab axis([xmin, xmax, ymin, ymax]) xlim([0, 10]) ylim([-2, 2]) ``` ### Grid and Box ```matlab grid on grid off grid minor box on box off ``` ### Axis Equal ```matlab axis equal % Same scale on both axes axis square % Square plot area ``` ## Multiple Plots ### Subplots ```matlab x = 0:0.1:2*pi; subplot(2, 2, 1) plot(x, sin(x)) title('Sine') subplot(2, 2, 2) plot(x, cos(x)) title('Cosine') subplot(2, 2, 3) plot(x, tan(x)) title('Tangent') subplot(2, 2, 4) plot(x, exp(x)) title('Exponential') ``` ### Using hold ```matlab plot(x, sin(x)) hold on plot(x, cos(x)) hold off legend('sin', 'cos') ``` ## Specialized 2D Plots ### Scatter Plot ```matlab x = rand(50, 1) * 10; y = rand(50, 1) * 10; colors = rand(50, 1); scatter(x, y, 50, colors, 'filled') colorbar ``` ### Bar Plot ```matlab categories = {'A', 'B', 'C', 'D'}; values = [15, 30, 25, 10]; bar(categories, values) ylabel('Count') % Stacked bar bar(categories, [15, 30; 25, 10], 'stacked') ``` ### Histogram ```matlab data = randn(1000, 1); histogram(data, 30) % 30 bins histogram(data, 'Normalization', 'pdf') ``` ### Pie Chart ```matlab sizes = [30, 25, 20, 15, 10]; labels = {'A', 'B', 'C', 'D', 'E'}; pie(sizes, labels) ``` ### Box Plot ```matlab data = randn(100, 4); boxplot(data, 'Labels', {'A', 'B', 'C', 'D'}) ylabel('Value') ``` ### Error Bars ```matlab x = 1:5; y = [10, 15, 12, 18, 20]; errors = [1, 2, 1.5, 2.5, 1]; errorbar(x, y, errors) ``` ## 3D Plotting ### 3D Line Plot ```matlab t = 0:0.1:10*pi; x = cos(t); y = sin(t); z = t; plot3(x, y, z) xlabel('x') ylabel('y') zlabel('z') title('Helix') ``` ### Surface Plot ```matlab [x, y] = meshgrid(-2:0.1:2, -2:0.1:2); z = x.^2 + y.^2; surf(x, y, z) xlabel('x') ylabel('y') zlabel('z') colorbar ``` ### Mesh Grid ```matlab [x, y] = meshgrid(-2:0.5:2, -3:0.5:3); % x and y are 2D grids for 3D plotting ``` ### Contour Plot ```matlab [x, y] = meshgrid(-2:0.1:2, -2:0.1:2); z = x.^2 + y.^2; contour(x, y, z, 20) % 20 contour levels contourf(x, y, z, 20) % Filled contours ``` ### 3D Scatter ```matlab x = rand(100, 1) * 10; y = rand(100, 1) * 10; z = rand(100, 1) * 10; colors = rand(100, 1); scatter3(x, y, z, 50, colors, 'filled') ``` ### Mesh and Surface Combined ```matlab [x, y] = meshgrid(-3:0.2:3); z = peaks(x, y); mesh(x, y, z) hold on surf(x, y, z) hold off ``` ## Plot Styling ### Colormaps ```matlab colormap jet colormap parula colormap gray colormap hot colormap cool colormap viridis ``` ### Lighting and View ```matlab [x, y] = meshgrid(-2:0.1:2); z = peaks(x, y); surf(x, y, z) shading interp lighting gouraud material metal camlight view(45, 30) % Azimuth, elevation ``` ### Transparency ```matlab [x, y] = meshgrid(-2:0.2:2); z = x.^2 + y.^2; surf(x, y, z, 'FaceAlpha', 0.5) % Semi-transparent ``` ## Annotations ### Text ```matlab plot(0:0.1:2*pi, sin(0:0.1:2*pi)) text(pi, 0, 'sin(\pi) = 0', 'FontSize', 12) ``` ### Arrows and Shapes ```matlab annotation('arrow', [0.2, 0.4], [0.8, 0.6]) annotation('rectangle', [0.2, 0.2, 0.1, 0.1]) annotation('line', [0.1, 0.3], [0.5, 0.5]) ``` ## Figure Management ### Creating Figures ```matlab figure(1) plot(x, y) figure(2) plot(x, z) ``` ### Saving Figures ```matlab % Save as image saveas(gcf, 'plot.png') saveas(gcf, 'plot.jpg') saveas(gcf, 'plot.pdf') saveas(gcf, 'plot.fig') % Export for editing print('-djpeg', 'plot.jpg') print('-depsc', 'plot.eps') ``` ### Closing Figures ```matlab close % Close current figure close all % Close all figures close(2) % Close figure 2 ``` ## Multiple Axes ```matlab x = 0:0.1:10; yyaxis left plot(x, sin(x)) ylabel('Sin') yyaxis right plot(x, exp(x/5)) ylabel('Exp') ``` ## Animations ### Simple Animation ```matlab x = 0:0.1:10; figure for i = 1:length(x) plot(x(1:i), sin(x(1:i))) xlim([0, 10]) ylim([-1, 1]) drawnow end ``` ## Summary - `plot()` for basic 2D line plots - Use `'Color', 'Marker', 'LineStyle'` for customization - `xlabel()`, `ylabel()`, `title()`, `legend()` for labels - `subplot()` for multiple plots in one figure - `surf()`, `mesh()` for 3D surface plots - `scatter()`, `bar()`, `histogram()` for specialized plots - `colormap()` to change colors - `saveas()` or `print()` to export figures