Matlab Graphics - Scatter Plots

Scatter Plots

Scatter plots are a basic graph type in MATLAB; their class is matlab.graphics.chart.primitive.Scatter.

Functions

• 2-D: scatter
• 3-D: scatter3—same usage as scatter

Scatter Properties

Scatter properties control the appearance and behavior of a Scatter object and are stored as a structure. Storing a plot as an object in a variable lets you inspect and edit each property:

p =
 
  Scatter with properties:
 
             Marker: 'o'
    MarkerEdgeColor: 'none'
    MarkerFaceColor: 'flat'
           SizeData: [1x200 double]
          LineWidth: 0.5000
              XData: [1x200 double]
              YData: [1x200 double]
              ZData: [1x0 double]
              CData: [1x200 double]
 
  Use GET to show all properties

A selection of marker properties follows.

Marker Symbol

• Field name: .Marker
• Default: 'o'
• Inputs: same as Marker Symbol

Width of Marker Edge

• Field name: .LineWidth
• Default: 0.5
• Inputs: numeric

Marker Outline Color

• Field name: .MarkerEdgeColor
• Default: 'flat'
• Inputs: 'flat', an RGB triplet, a hexadecimal color code, a color name, or a short name
  • 'flat' uses the CData values
  • 'auto' uses the same color as the Color property of the axes

Marker Fill Color

• Field name: .MarkerFaceColor
• Default: 'none'
• Inputs: 'flat', 'auto', an RGB triplet, a hexadecimal color code, a color name, or a short name
  • 'flat' uses the CData values
  • 'auto' uses the same color as the Color property of the axes

Marker Edge Transparency

• Field name: .MarkerEdgeAlpha
• Default: 1
• Inputs: scalar in [0,1], or 'flat'
  • To set per-point edge transparency, set AlphaData to a vector the same size as XData and set MarkerEdgeAlpha to 'flat'

Marker Face Transparency

• Field name: .MarkerFaceAlpha
• Default: 1
• Inputs: scalar in [0,1], or 'flat'

Examples

2-D

x = linspace(0,3*pi,200);
y = cos(x) + rand(1,200);
sz = linspace(1,25,length(x));
c = linspace(1,1000,length(x));
scatter(x,y,sz,c,'filled')

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3-D

% Load data on ozone levels
load ozoneData Ozone Temperature WindSpeed SolarRadiation
% Calculate the ozone levels
z = (Ozone).^(1/3);
response = z;
% Make a color index for the ozone levels
nc = 16;
offset = 1;
c = response - min(response);
c = round((nc-1-2*offset)*c/max(c)+1+offset);
% Create a 3D scatter plot using the scatter3 function
figure
scatter3(Temperature, WindSpeed, SolarRadiation, 30, c, 'filled')
view(-34, 14)
% Add title and axis labels
title('Ozone Levels')
xlabel('Temperature')
ylabel('Wind Speed')
zlabel('Solar Radiation')
% Add a colorbar with tick labels
colorbar('Location', 'EastOutside', 'YTickLabel',...
    {'2 ppm', '4 ppm', '6 ppm', '8 ppm', ...
    '10 ppm', '12 ppm', '14 ppm'})

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