Split bar chart with specific colours for each variable

I have 143 data points (neurons) which have "preferred firing directions" (labelled as 1:8 in my 'ydata'). I'm trying to create 6 separate barcharts to show when the neurons have the same firing direction for the 'Go' signal (column 1 of 'ydata') and the 'Instruction' signal (column 2 of 'ydata'). I have tried everything I can think of to label the 'Go' signal with one color and the 'Instruction' signal with another. I know this question has been asked before in slightly different ways, but I've tried a lot of the answers and the best I've got is that it will set all of my bars to the same color and gives me an error whenever I try to index the other color. I'm not sure what I'm doing wrong here.

My dataset is saved in the file 'MatLAB Help.mat' and here is the code I am trying to run:

for k = 1:length(xdata)
    if k <= 24
        nexttile(1);
        hold on
        b1 = bar(xdata(k), ydata(k));
        b1(1).FaceColor = [0 0.447 0.741];
        b1(2).FaceColor = [0.85 0.325 0.098];
    elseif k >=25 && k <= 48
        nexttile(2); 
        hold on
        bar(xdata(k), ydata(k));
    elseif k >= 49 && k <= 72
        nexttile(3)
        hold on
        bar(xdata(k), ydata(k));
    elseif k >= 73 && k <= 96
        nexttile(4)
        hold on
        bar(xdata(k), ydata(k));
    elseif k >= 97 && k <= 120
        nexttile(5)
        hold on
        bar(xdata(k), ydata(k));
    else
        nexttile(6)
        hold on
        bar(xdata(k), ydata(k));
    end
end

For some reason, it keeps giving me the error:

Unrecognized property 'FaceColor' for class 'matlab.graphics.GraphicsPlaceholder'.

Any help would be greatly appreciated. Thanks!

Answer 1

[Voss]

ydata(k) is a single element of ydata, so

b1 = bar(xdata(k), ydata(k));

produces a single bar, i.e., b1 is of length 1. Trying to access b1(2).FaceColor is what generates the error you got.

If you want two bars, perhaps you mean

b1 = bar(xdata(k), ydata(k,:));

in which ydata(k,:) is the kth row of ydata, so that's a 1x2 vector and b1 is also 1x2.

load('MatLAB Help.mat')
k = 1;

% original generates an error:
figure
b1 = bar(xdata(k), ydata(k))

b1 = 
  Bar with properties:

    BarLayout: 'grouped'
     BarWidth: 0.8000
    FaceColor: [0 0.4470 0.7410]
    EdgeColor: [0 0 0]
    BaseValue: 0
        XData: 1
        YData: 1

  Use GET to show all properties

try % to catch the error, so subsequent code can execute
    b1(1).FaceColor = [0 0.447 0.741];
    b1(2).FaceColor = [0.85 0.325 0.098];
catch e % to report the error
    disp(e.message);
end

Unrecognized property 'FaceColor' for class 'matlab.graphics.GraphicsPlaceholder'.

% using (k,:) indexing gives two bars
figure
b1 = bar(xdata(k), ydata(k,:))

b1 = 
  1×2 Bar array:

    Bar    Bar

b1(1).FaceColor = [0 0.447 0.741];
b1(2).FaceColor = [0.85 0.325 0.098];

[Jessica Leverett]

This worked!! Thank you so much!

[Voss]

You're welcome! Any questions, let me know.