Function findobj does not find an object (?)

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Daigo
Daigo on 10 Jan 2022
Commented: Daigo on 10 Jan 2022
I have a function to make a plot of two vectors t and y, and mark the minimum value of y as a red asterisk marker.
function m = plot_cos(y, t)
figure;
plot(t, y, 'b--'); hold on;
[m,I] = min(y);
s = scatter(t(I),m);
s.MarkerEdgeColor = 'r';
s.Marker = '*';
end
I should be able to use a 'findobj' function to see that the Marker property is set to be the asterisk, that is,
t = linspace(0,2*pi,100);
y = cos(t);
m = plot_cos(y, t)
h = findobj(gcf,'Type', 'Line');
assert(strcmp(h.Marker, '*'));
However, the assertion in the last line of the code fails. Is there any way to set the marker type to asterisk such that 'findobj' can find it?

Accepted Answer

Cris LaPierre
Cris LaPierre on 10 Jan 2022
assert is for comparison. Your code is checking if the marker of the found line is an asterisk. It is not, so the result is the assertion fails.
Your asterisk was created by scatter, so is a scatter object. To find it, your type should be 'scatter'.
t = linspace(0,2*pi,100);
y = cos(t);
m = plot_cos(y, t)
m = -0.9995
h = findobj(gcf,'Type', 'Scatter');
assert(strcmp(h.Marker, '*'));
function m = plot_cos(y, t)
figure;
plot(t, y, 'b--'); hold on;
[m,I] = min(y);
s = scatter(t(I),m);
s.MarkerEdgeColor = 'r';
s.Marker = '*';
end

More Answers (1)

Matt J
Matt J on 10 Jan 2022
h = findobj(gcf,'Type', 'Scatter');

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