Contour is plotting my data in reflected order?

I'm using flip to solve this but is this intentional?

[KSSV]

It depends on your data.

[Amanda Liu]

My data:

The temperature is higher at the bottom row in my data, so contour will automatically arrange the top to be higher temperature and reflect my data?

Answer 1

[Joseph Cheng]

From a quick test you might not be asigning the x and y values when performing your contour() function. by doing so matlab will automatically assign the row and column indexing to match the matrix. So in your example your max data is at the bottom row which is technically the higher value in cartesian coordinates of row 10 (ie y axis 10). you can get around this by defining your x and y values to plot against.

so matrix position (1,1) (row 1, column 1) is top left, but when displayed it'll be bottom left.

%dummy data
[x y]=meshgrid(-5:1:5,-5:1:5);
z = x+(2*y+4).^2;
% plot with just z and then specifying the rows and columns of the matrix z
figure(1),subplot(211),contour(z),colorbar
title('original contour')
subplot(212),contour(-5:1:5,5:-1:-5,z),colorbar

[Amanda Liu]

I've actually already assigned x and y in my contour()...

subplot(2,1,1);
[C,h]=contourf(x,y,flip(T));
clabel(C,h);
colorbar;
xlabel('x (mm)');
ylabel('y (mm)');

[Joseph Cheng]

oh yes but what is x and y? does it follow what i'm discussing here where the first y value y(1) is your most negative or most positive value of y.

[Amanda Liu]

from 0 to n, yes

n = 10;
X = linspace(0,L,n);        % x nodes
Y = linspace(0,H,n);        % y nodes
[x y] = meshgrid(X,Y);

[Joseph Cheng]

so then it would mean that the first row would be denoted at y values of 0 and the last row would be H which i'm assuming here is a positive value. which is why it plots flipped.

[Amanda Liu]

Ohh I think I understand now. I'm a total beginner at this. Thank you! ;)

Answer 2

[Steven Lord]

Are you trying perhaps to put the contour plot on top of another graphics object, an image perhaps or maybe a pcolor? If so, see the "Change Direction of Coordinate System" example on the documentation page for the axis function.

[Amanda Liu]

I'm using subplot only. "Change Direction of Coordinate System" changes all my x,y,T axis but I only want to change the T axis.