How to add text on the figure without unknown x and y coordinates ?

Hi i have a csv file the problem is my data has random x,y values so it changes according to machine but i want to display a value on the figure. I tried something like this v = (intensity/intensity_max)*100; text(x,y,(v) but it didn't work because of the x and y values. How can i overcome on this problem ?

[Steven Lord]

See this previous discussion for more context.

[Onur Hakverdi]

hi it doesn't include a solution for my issue.

Answer 1

[Image Analyst]

The problem was you were printing an entire array of thousands of elements instead of a single number.

This seems to work. Adapt as needed.

% Demo to print the peak on a spectrogram.
clc;    % Clear the command window.
fprintf('Beginning to run %s.m ...\n', mfilename);
close all;  % Close all figures (except those of imtool.)
clearvars;
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 18;

inputFolder = pwd;
fullFileName = fullfile(inputFolder, 'spectroscopy.csv')
data = csvread(fullFileName);
wavelength = data(:,2);
intensity = data(:,1);
[intensity_max, index] = max(intensity)
wavelength_max = wavelength(index);
plot(wavelength,intensity, 'b-');
hold on;
plot(wavelength_max, intensity_max, 'ro', 'MarkerSize', 11, 'LineWidth', 2);
xlabel('Wavelength', 'FontSize', fontSize);
ylabel('Intensity', 'FontSize', fontSize);
grid on;

% Compute normalized intensity vector, but strangely enough, we never use it.
normalizedIntensity = (intensity / intensity_max) * 100;

% Print max value next to the peak of the curve.
xText = wavelength_max
yText = intensity_max
textLabel = sprintf('  The Max Intensity is %.7f', intensity_max)
text(xText, yText, textLabel, 'horizontalalignment', 'left', 'Color', 'r', 'FontWeight', 'bold', 'FontSize', 14);

% Give a title.
if  333800 < intensity_max && intensity_max < 345100
	title('Cu-I', 'FontSize', fontSize)
elseif 862000 < intensity_max && intensity_max < 90550
	title('Al-I', 'FontSize', fontSize)
elseif 4200 < intensity_max && intensity_max < 5720
	title('C-I', 'FontSize', fontSize)
elseif 209 < intensity_max && intensity_max < 211
	title('C-II', 'FontSize', fontSize)
else
	title('Unknown species', 'FontSize', fontSize);
end
outputFolder = 'C:\Plots\';
if ~isfolder(outputFolder)
	% Create folder if it dows not exist.
	mkdir(outputFolder);
end
fullOutputFileName = fullfile(outputFolder, 'Plot.png')
% saveas(gcf, fullOutputFileName); % Old: pre R2020a
% exportgraphics(gca, fullOutputFileName);  % New: R2020a or newer

fprintf('Done!\n');

[Onur Hakverdi]

That is awesome job. I just only wanted a percentage value on the figure, but logic is true. Instead of "The Max Intensity is 209.45", I wanted "The percentage of is %90.xx" like this. I couldn't explain my problem very well, so probably people were thinking wrong.

[Image Analyst]

@Onur Hakverdi, of course the peak is at 100%, and all the rest of the thousands of values are like 50% or so. And surely you don't want thousands of text labels on there - you wouldn't be able to see your data.

If you don't want what I put, then you can change sprintf() to have it say exactly what you want. Just don't put the whole array name into sprintf() or it will try to use each one of those thousands of array elements over and over again with the format string.

Answer 2

[Scott MacKenzie]

To print 'hello' in the center of the figure... (adjust accordingly)

ax = gca;
x = ax.XLim(1) + (ax.XLim(2) - ax.XLim(1)) / 2;
y = ax.YLim(1) + (ax.YLim(2) - ax.YLim(1)) / 2;
text(x, y, 'hello', 'horizontalalignment', 'center');

[Onur Hakverdi]

by the way how can I print a numerical calculated value ?

[Scott MacKenzie]

Using sprintf to build up a string containing a calculated value is a common approach:

x = 1.23; % value to print
s = sprintf('The value is %.2f', x);
text(x, y, s);

[Onur Hakverdi]

it gives error for y

[Scott MacKenzie]

Oops, my mistake. I shouldn't have used x for the variable, since we are using x and y as the screen coordinates. This will work:

a = 1.23; % value to print
ax = gca;
x = ax.XLim(1) + (ax.XLim(2) - ax.XLim(1)) / 2;
y = ax.YLim(1) + (ax.YLim(2) - ax.YLim(1)) / 2;
s = sprintf('The value is %.2f', a);
text(x, y, s, 'horizontalalignment', 'center');

[Onur Hakverdi]

it has worked but when I tried to change the value in terms of an equation it's giving a error.

[Onur Hakverdi]

[Onur Hakverdi]

Warning: Error creating or updating Text

Error in value of property String

Text length might be too long to display.

> In defaulterrorcallback (line 12)

In print (line 36)

In saveas (line 181)

In Untitled3 (line 30)

Warning: Error creating or updating Text

Error in value of property String

Text length might be too long to display.

> In defaulterrorcallback (line 12)

In alternatePrintPath

In alternatePrintPath

In alternatePrintPath

In print (line 83)

In saveas (line 181)

In Untitled3 (line 30)

Warning: Error creating or updating Text

Error in value of property String

Text length might be too long to display.

> In defaulterrorcallback (line 12)

In matlab.graphics.internal/mlprintjob/setPaintDisabled

In alternatePrintPath

In alternatePrintPath

In onCleanup/delete (line 80)

In alternatePrintPath

In print (line 83)

In saveas (line 181)

In Untitled3 (line 30)

>> error message

[Scott MacKenzie]

Well that's due to something else.

What's the complete error?

Also, please post the code rather than an image of the code. And if you can post/upload the data file, that would help as well.

[Onur Hakverdi]

m file is here but it requires csv file.

[Onur Hakverdi]

csv file is here.