Different coloured regions on a scatter plot

I have a g-g diagram where I want to display different regions in different colours (so right acceleration is one colour, pure acceleration is a different one, left acceleration is different, pure left cornering is different and so on). I was able to overlay a plot on top to show left, right and in the middle like this:

sz = 8

scatter(Lat_A, Long_A, sz, 'filled')
ylabel("Longitudinal Acceleration /g")
xlabel("Lateral Acceleration /g")

threshold = 0.4
right = Lat_A(Lat_A>threshold)
left = Lat_A(Lat_A<-threshold)

hold on;
scatter(right, Long_A(Lat_A > threshold), sz, 'g', 'filled'); 
scatter(left, Long_A(Lat_A < -threshold), sz, 'r', 'filled'); 
hold off;

However, I'm struggling to factor in the braking and acceleration the same way on the same plot. In simple terms, I want to show (x>0.4, y>0.4), (x<-0.4, y>0.4), (abs(x)< 0.4, y>0.4) etc. as different colours. I'm pretty new to MATLAB so any help would be appreciated.

Answer 1

[Image Analyst]

Try this:

fontSize = 25;
numPoints = 3000;
lateralAcceleration = 7 * rand(numPoints, 1) - 3.5;
longitudinalAcceleration = 4.2 * rand(numPoints, 1) - 3;
% Assign colors (determined via Photoshop from screenshot of sample image).
red = [254, 1, 2] / 255;
blue = [0, 81, 148] / 255;
green = [0, 177, 80] / 255;
purple = [113, 50, 162] / 255;
yellow = [254, 192, 0] / 255;
brown = [116, 63, 32] / 255;
orange = [229, 111, 35] / 255;
cyan = [39, 161, 254] / 255;
% Initialize size and have them be all black initially.
markerColors = zeros(numPoints, 3);
% Assign red markers
indexes = longitudinalAcceleration > 0.25 & lateralAcceleration < -0.3;
markerColors(indexes, :) = repmat(red, sum(indexes), 1);
% Assign purple markers
indexes = longitudinalAcceleration > 0.25 & lateralAcceleration > -0.3 & lateralAcceleration < 0.3;
markerColors(indexes, :) = repmat(purple, sum(indexes), 1);
% Assign green markers
indexes = longitudinalAcceleration > 0.25 & lateralAcceleration > 0.3;
markerColors(indexes, :) = repmat(green, sum(indexes), 1);
% Assign blue markers
indexes = longitudinalAcceleration < -0.3 & lateralAcceleration < -0.3;
markerColors(indexes, :) = repmat(blue, sum(indexes), 1);
% Assign brown markers
indexes = longitudinalAcceleration < -0.3 & lateralAcceleration > -0.3 & lateralAcceleration < 0.3;
markerColors(indexes, :) = repmat(brown, sum(indexes), 1);
% Assign yellow markers
indexes = longitudinalAcceleration < -0.3 & lateralAcceleration > 0.3;
markerColors(indexes, :) = repmat(yellow, sum(indexes), 1);
% Assign orange markers
indexes = abs(longitudinalAcceleration) <= 0.3 & lateralAcceleration < -0.3;
markerColors(indexes, :) = repmat(orange, sum(indexes), 1);
% Assign cyan markers
indexes = abs(longitudinalAcceleration) <= 0.3 & lateralAcceleration > 0.3;
markerColors(indexes, :) = repmat(cyan, sum(indexes), 1);
% Do the scatterplot
scatter(lateralAcceleration, longitudinalAcceleration, 35, markerColors, 'filled');
grid on;
xlabel('Lateral Acceleration', 'FontSize', fontSize);
ylabel('Longitudinal Acceleration', 'FontSize', fontSize);
xline(0.3, 'LineWidth', 3);
xline(-0.3, 'LineWidth', 3);
yline(0.3, 'LineWidth', 3);
yline(-0.3, 'LineWidth', 3);

You can use text() to add the colored text labels.

[Felicity]

Thank you!

Answer 2

[Image Analyst]

"just colouring the points would be enough" <== One of the inputs to scatter is a vector of colors that you want each marker point to have.

help scatter

 scatter - Scatter plot

    Syntax
      Vector and Matrix Data
        scatter(x,y)
        scatter(x,y,sz)
        scatter(x,y,sz,c)
        scatter(___,"filled")
        scatter(___,mkr)

      Table Data
        scatter(tbl,xvar,yvar)
        scatter(tbl,xvar,yvar,"filled")

      Additional Options
        scatter(ax,___)
        scatter(___,Name,Value)
        s = scatter(___)

    Input Arguments
      x - x-coordinates
        scalar | vector | matrix
      y - y-coordinates
        scalar | vector | matrix
      sz - Marker size
        36 (default) | numeric scalar | row or column vector | matrix | []
      c - Marker color
        color name | RGB triplet | matrix of RGB triplets |
        vector of colormap indices
      mkr - Marker symbol
        "o" (default) | "+" | "*" | "." | "x" | ...
      "filled" - Option to fill interior of markers
        "filled"
      tbl - Source table
        table | timetable
      xvar - Table variables containing x-coordinates
        one or more table variable indices
      yvar - Table variables containing y-coordinates
        one or more table variable indices
      ax - Target axes
        Axes object | PolarAxes object | GeographicAxes object

    Name-Value Arguments
      MarkerEdgeColor - Marker outline color
        "flat" (default) | RGB triplet | hexadecimal color code | "r" |
        "g" | "b" | ...
      MarkerFaceColor - Marker fill color
        "none" (default) | "flat" | "auto" | RGB triplet |
        hexadecimal color code | "r" | "g" | "b" | ...
      LineWidth - Width of marker edge
        0.5 (default) | positive value
      ColorVariable - Table variable containing color data
        table variable index

    Output Arguments
      s - Scatter object
        Scatter object | array of Scatter objects

    Examples
      openExample('graphics/CreateScatterPlotExample')
      openExample('graphics/VaryCircleSizeExample')
      openExample('graphics/VaryCircleColorExample')
      openExample('graphics/ScatterColorPaletteExample')
      openExample('graphics/VaryCircleSizeandColorExample')
      openExample('graphics/SpecifyMarkerSymbolExample')
      openExample('graphics/SpecifyMarkerPropertiesExample')
      openExample('graphics/ScatterAlphaDataExample')
      openExample('graphics/ScatterTableExample')
      openExample('graphics/ScatterTableSizeColorExample')
      openExample('graphics/ScatterSpecifyAxes19bExample')
      openExample('graphics2/SetScatterObjectPropertiesExample')

    See also hold, plot, scatter3, bubblechart, swarmchart,
      Scatter Properties

    Introduced in MATLAB before R2006a
    Documentation for scatter
       doc scatter

    Other uses of scatter

       tall/scatter