I having trouble displaying each value next to the correct data point on stem plot.

I have an array of 1x20 containing the peak amplitude values and instead of displaying each text value next to the correct data point, it prints the entire array contents next to every data point.

PC = {0, NaN, -34.30, -39.90, -46.20, -47.80, -55.20, -52.20, -56.80, -60.90, -70.80, NaN, NaN, NaN, NaN, -72.80, NaN, NaN, NaN, NaN}

x=1:1:20;
subplot(3,1,3);
stem(x,RC);
text=text(x, RC, sprintf('%6.3f', RC));
set(text,'Rotation',60,'HorizontalAlignment','left','VerticalAlignment','baseline');
grid;
xlim([0, 20]);
title('Relative contribution of each harmonic ')
xlabel('Odd Harmonics');
ylabel('Contribution');

Answer 1

[Star Strider]

You can avoid the loop by using compose (or the undocumented sprintfc).

PC = {0, NaN, -34.30, -39.90, -46.20, -47.80, -55.20, -52.20, -56.80, -60.90, -70.80, NaN, NaN, NaN, NaN, -72.80, NaN, NaN, NaN, NaN}
x = 1:numel(PC);

figure
stem(x, [PC{:}], 'filled')
grid
xlim([0 20])
lbls = compose('%.2f', [PC{:}]);
text(x, [PC{:}], lbls, 'HorizontalAlignment','center', 'VerticalAlignment','top', 'FontSize',8)

[Michael Andersson]

Yes, thank you, that works for me and is simple enough for me to follow.

[Star Strider]

As always, my pleasure!

Answer 2

[Image Analyst]

I had made up this answer to your duplicate question, when you deleted it and I couldn't post it. So here it is:

v = rand(1, 40);
plot(v, 'b-', 'LineWidth', 2);
grid on;
[peakValues, indexesOfPeaks] = findpeaks(v);
hold on;
stem(indexesOfPeaks, peakValues, 'r.', 'LineWidth', 2, 'MarkerSize', 35);
for k = 1 : length(peakValues)
	textLabel = sprintf('(%d, %.2f)', indexesOfPeaks(k), peakValues(k));
	% Place text above the point by adding a little bit to the y value.
	text(indexesOfPeaks(k), peakValues(k) + 0.05, textLabel, ...
		'HorizontalAlignment', 'center', ...
		'FontWeight', 'bold', ...
		'FontSize', 12, ...
		'Color', 'r');
end

We can't run the code you posted here because you didn't include RC, only PC. And if we change PC to RC, it still doesn't run.

Basically you need to put text() into a loop where you put up only one at a time.

[Michael Andersson]

Thanks, I think I will use this method for some of the other data I need to analyse and display. Sorry if my posting is a bit hard to follow, this is the first question I have ever posted.