add xy coordinates to a graph

hi, i have a graph like this picture, local maxmimus are shown with red points, but i also would like to show the related xy coordinates on graph by adding commands to existing code,not with data curser. please help me if you can

Answer 1

[Image Analyst]

Do you mean you just want to put a text label near it?

indexToLabel = 42; % or whatever.
textString = sprintf('x = %.2f, y = %.2f', x(indexToLabel), y(indexToLabel));
text(x(indexToLabel), y(indexToLabel), textString);

Adjust the x, and y as necessary in text() to move the location of the label.

[maryam]

tnx for ur answer, please help me more! i used ur code as below:

[pks,locs]=findpeaks(r,'minpeakdistance',5,'THRESHOLD',100);% finding max

indexToLabel=[pks,locs];

textString = sprintf('x = %.2f, y = %.2f', x(indexToLabel), y(indexToLabel));

text(x(indexToLabel), y(indexToLabel), textString);

this error appeared on screen: Subscript indices must either be real positive integers or logicals.

i couldn't understand the meaning of that :-(

could u plz explain what should i do?

[Image Analyst]

You need to get the x,y coordinates. Plus you have an array whereas I had just a single index (42). You can put it in a loop over indexToLabel where you call text once for each peak location.

[Sean Haines]

how would you add a \r to this label?

[Image Analyst]

Put \n into the string:

numPoints = 20;
x = sort(rand(1, numPoints));
y = rand(1, numPoints);
plot(x, y, 'b.-', 'MarkerSize', 25);
grid on;
[~, indexToLabel] = max(y); % label the highest point, or whatever you want.
textString = sprintf('x = %.2f\ny = %.2f', x(indexToLabel), y(indexToLabel));
text(x(indexToLabel), y(indexToLabel), textString, 'FontSize', 20, 'Color', 'r');