How to draw lines through elements with same value

Hello! I have a small question here:

Suppose I have a matrix A, it looks like:

1 2 3 4 5 6 7

2 1 3 5 4 6 9

4 1 3 8 6 7 5

Now I want to plot the lines through points with value=1 and value=5 into a 2D plot, where x axis is created by for loop:

for i = 10:1:17;
end

and y axis is created by for loop:

for j = 2.5:0.1:2.7;
end

Can someone help me on this? It is possible to make the lines as smooth as possible?

Thanks a lot!

Answer 1

[Walter Roberson]

selected = (A==1) | (A==5);
image(selected, 'XData', [10 16], 'YData', [2.5 2.7]);

Possibly you would prefer

contour(10:16, 2.5:0.1:2.7, A, [1 5])

Note my correction of the 10:17 to 10:16 as you only have 7 elements rather than 8

[James Lorringer]

Hi, thanks, it worked perfectly. If I want to put the value (1 and 5) on or beside the line as a note, could you please help me on that? Thanks!

[Walter Roberson]

[C,h] = contour(10:16, 2.5:0.1:2.7, A, [1 5]);
clabel(C,h);

[James Lorringer]

Great! Thanks!