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How do I flip an image without affecting the Y Axis?

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Ted Baker
Ted Baker on 21 Jul 2020
Commented: Ted Baker on 21 Jul 2020
I'm trying to plot the example file using the following code:
close all;
input = 'example.txt';
data = readmatrix(input);
filename = input(1:end-4);
filename = [filename '.png'];
x = data(:,3);
v = data(:,9);
id = find(x == 0);
imdata = reshape(v,id(2)-1,[])';
im = rot90(imdata,2);
im = fliplr(im);
xdata = 1:1:56;
ydata = 6.3:0.275:19.775;
flip(ydata);
imagesc(im, 'XData', xdata, 'YData', ydata);
colorbar;
colormap(jet);
xlabel('xaxis');
ylabel('yaxis');
title('title');
axis on
xticks(xdata);
set(gca, 'XTick', (1 : 5 : 56) );
yticks(ydata);
set(gca, 'YTick', (6.3: 1.375 :19.775) ); % plot every 5th tick
set(gca,'YDir','normal')
Where I would like the red corner of the output plot in the top right, blue corner in bottom left, as per this image:
However the Y axis nees to go from ~6 in the bottom left to ~19 in the top left - the axis in this image are reversed. What am I doing wrong with my code? I've tried using ydata straight, flipping it, etc but that hasn't worked. Whenever I set YDir it always flips the image so that the red in at the bottom, but then the axis looks ok.
Thanks in advance.

Accepted Answer

Mehmed Saad
Mehmed Saad on 21 Jul 2020
Edited: Mehmed Saad on 21 Jul 2020
Use flip (or fliplr,flipud)
figure,
subplot(211)
imagesc(im, 'XData', xdata, 'YData', ydata);set(gca,'YDir','normal')
subplot(212)
imagesc(im, 'XData', xdata, 'YData', fliplr(ydata));set(gca,'YDir','normal')
colormap('jet')

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