Plotting piecewise, data from matrices/vectors

This is how my plot looks.

Preferably it would look like this both in the start and in the end (for both red and blue).

I have tried to use:

P = [...]'; % The data for the blue one
pw = piecewise(cond1,val1,cond2,val2,...)
   % P as val1

I want it to go straight down to 0 after the last 780, not gradually as seen in the first picture.

But I can't get it to work. Any suggestions as to how I could acheive this?

Answer 1

[Walter Roberson]

To go straight down, you need to duplicate the x coordinate with the two different y values.

stairs() automatically does the coordinate duplication, but it does it for all the points, which is not what you want, so you will need to duplicate the coordinate yourself.

Or you could add a second x coordinate that is marginally larger than the place you want to plunge; you would only be able to see the difference compared to duplicated coordinates if you zoomed way way in, but there are some cases such as interp1() where duplicated coordinates give you problems.

[Jørgen Myklebust]

Although quite manual I went with the marginally larger x-solution, adding extra data-points. Thanks!

For others with similar issues: All I had to do was add another zero after the last 780 in P aswell as manually creating x:

x =[1 2 3 4 ... 51 51.0001 52 53  54];
plot(x,P)

Is there an easy way to do this with code and not manually? Something like the usual:

x =[1:1:53]'

[Walter Roberson]

If you know the index then

x = [x(1:idx), x(idx)+0.0001, x(idx+1:end)];
P = [P(1:idx), 0, P(idx+1:end)];

[Jørgen Myklebust]

Great! I do :)