How do I access the axes handles of a confusion matrix?

Hi there, I am trying to plot something similar to the photo below (although clearly with a smaller font size), with the same axes labels (actual/predicted) and axes tick marks (class numbers):

The code I was implementing to generate the plot throws the following error when attempting to access the XLabel property of the Xaxis: 'No appropriate method, property or field'XLabel' for class 'matlab.ui.container.Menu'.

I think I am accessing the axes fields incorrectly using the following code:

figure(1)
plotconfusion(known_labels, predicted_labels)
fh = gcf;
ax = gca;
ax.FontSize = 8;
set(findobj(ax,'type','test'),'fontsize',3);
ah = fh.Children(2);
ah.XLabel.String = 'Actual';
ah.YLabel.String = 'Predicted';
ax.XTickLabel = class_labels;
ax.YTickLabel = class_labels;
title('Confusion Matrix 1', 'Fontsize',14)
set(gcf,'color','w');
hold off

Any help with how to do this correctly would be greatly appreciated. Thanks!

Answer 1

[Adam Danz]

You're accessing the XTickLabel field correctly but you're trying to enter a 'matlab.ui.container.Menu' object rather than a cell array of strings (or a numeric vector).

The XTickLabel controls the x tick mark labes. Look at the value of "class_labels" in your code (we don't have access to this). It doesn't specify tick labels.

Also, you could improve how you're getting the axis handle. The plotconfusion() function outputs the figure handle.

fh = plotconfusion(known_labels, predicted_labels); 

fh.Children(2).XLabel.String = 'Actual';
fh.Children(2).YLabel.String = 'Predicted';

% Examples of x tick labels (for a matrix with 11 columns)
fh.Children(2).XTickLabel = {'a' 'b' 'c' 'd' 'e' 'f' 'g' 'h' 'i' 'j' 'k'};
fh.Children(2).XTickLabel = 200:210

[pldr-bny]

Hi Adam, thanks for responding. I have edited my code as you suggested and have converted my class_label into a cell array of strings. Code below:

figure(1)
fh = plotconfusion(known_labels, predicted_labels);
fh.Children(2).XLabel.String = 'Actual';
fh.Children(2).YLabel.String = 'Predicted';
fh.Children(2).XTickLabel = class_labels;
fh.Children(2).YTickLabel = class_labels;
title("Confusion matrix 1", 'FontSize', 14)
set(gcf,'color','w')

However, I am still getting the same error: 'No appropriate method, property or field 'XLabel' for class matlab.ui.container.Menu'. Is there anything else I need to do in lines 3 and 4 of this code?

Thanks

[Adam Danz]

Could you share the content stored in "class_labels"? If it's really long, you could share a sample of it so I can see what it is. For example,

class_labels
ans = 
    {'label1', 'label2', 'label3', ....}

[pldr-bny]

Sure yes, here it is:

class_labels = {"01"} {"02"} {"03"} ...

It is a 1x71 cell array.

[Adam Danz]

I'm not familiar with that format. Did you copy/paste that from your command window or did you type that out?

If the format is correctly represented as a cell array, it works.

figure
axes
xlim([0 4])
class_labels = {"01", "02", "03"};
set(gca, 'xtick', 1:3, 'XTickLabel', class_labels)

% notice the difference between this output below and the one you shared
>> class_labels = {"01", "02", "03"}
class_labels =
  1×3 cell array
    {["01"]}    {["02"]}    {["03"]}

If the output you shared was copy-pasted and not typed, what's the result of: class(class_labels) (it should be 'cell')

[pldr-bny]

Calling class(class_labels) returns 'cell' and the variable description is 71x1 cell array.

I tried converting class_labels to a vector of doubles but I am still getting the original error. When I pass {"01", "02" .....} directly to the XTickLabel object, again I get the original error.

Could there be anything else going wrong here?

[Adam Danz]

This line below (from your penultimate comment) doesn't appear to be a cell array. Could you copy-paste the variable from the command window? How was this variable created? Maybe you could attach that variable to an mat file so I could look at it. The format of this line below is strange to me.

class_labels = {"01"} {"02"} {"03"} ...