Plotting Matrix points

Hello everyone!

I have a 2 by 10 matrix:

B =

   28.7636   27.7497
   26.7351   25.7208
   23.6934   22.6793
   20.6512   19.6371
   18.6241   17.6092
   15.5820   14.5679
   13.5537   11.5246
   10.5116    9.4974
    8.4835    6.4551
    5.4414    4.4273

I am trying to figure out how to plot these matrix points in pairs:

28.7636 27.7497 % start of first point and end of first point

26.7351 25.7208 % start of 2nd point and end of 2nd point

And so on...

I haven't been able to determine the correct plot syntax to accomplish this. Matlab has so many commands when it comes to plotting I dont even know where to start!

Thank in advance!

[Sean de Wolski]

Could you find an example image on google images or somewhere (or make one in powerpoint) of what you want to see. There's clearly a communication boundary since four of us are missing the target.

[B_Richardson]

Ok, I will see what I came come up with

[B_Richardson]

I have made a crudely drawn image of what I'm trying to accomplish to clear up any misunderstanding my poor descriptions have caused!

http://postimage.org/image/2wwighvs4/

[B_Richardson]

Guys, I'm going to post this in a new question because this one has become too confusing! I;m going to name it Plotting Matrix points: 2

[Fangjun Jiang]

Your figure is almost done with the Horizontal lines solution I provided.

Answer 1

[Walter Roberson]

If you do not want to loop over line(B(K,1),B(K,2)) then you can use this trick:

X = reshape(B(:,1),2,[]);
X(3,:) = nan;
X = X(:);
Y = reshape(B(:,2),2,[]);
Y(3,:) = nan;
Y = Y(:);
plot(X,Y)

This introduces a nan after every second point, and then zips everything back together. nan are treated as indicating a break in plotting.

Jan, I think it was, pointed out to me that inf could be used in place of nan for this purpose, and that most modern cpus handle inf more quickly than they handle nan.

[Fangjun Jiang]

This figure shows 5 lines. I assume the OP wants to draw 10 lines.

[Walter Roberson]

Good point. Okay, in that case,

plot(reshape([B, nan(size(B,1),1)],1,[]))

[Walter Roberson]

plot(ndgrid(1:size(B,1),1:size(B,2)).',B.','b-o')

[B_Richardson]

I think this might work. Let me translate in into GUIDE and see how it looks with the correct data. Its very similar to the effect of stem.

[Walter Roberson]

plot(repmat(ConstantX, 1, size(B,1)), B.', 'b-o')

Answer 2

[Sean de Wolski]

line(B(:,1),B(:,2))

maybe?

What do you mean by start of first and end?

[B_Richardson]

I will try to illustrate:

_____--___--____--____

each dash represents a matrix element the solid line is the overall length of a video:

dash 1,2 = 28.7636 27.7497

dash 3,4 = 26.7351 25.7208

dash 5,6 = 23.6934 22.6793

It doesnt have to appear exactly like that but the idea is to display them in order of pairs from start to finish. This is for segmentation of a video. I'm going to plot them over the over length of the video in an GUIDE axis.

Answer 3

[Fangjun Jiang]

Not enough information. Your B is 10x2 matrix, not 2x10. Maybe:

a=[1:10;1:10];
line(a,B');

Horizontal lines:

line(B',zeros(2,10));
hold on;
plot(B,zeros(10,2),'o');

Vertical lines:

line(zeros(2,10),B');
hold on;
plot(zeros(10,2),B,'o');

[B_Richardson]

Oppps, yes I meant 10X2!

[Fangjun Jiang]

Then use line(B',a)

[Fangjun Jiang]

or line(B',ones(2,10))

[Fangjun Jiang]

or could be line(B',zeros(2,10))

[B_Richardson]

The elements are points of interest in a video. I am trying to visually display start and stop times of repetitions of an exercise. 10 reps in the video and each rep has a start and end, so 20 elements with the first coloumn being the start of each rep and the 2nd the end of each rep:

Start...stop...Rep

1........2......1

3........4......2

5........6......3

................

................

19.......20.....10

So far I tried this:

plot(reshape([B, nan(size(B,1),1)],1,[]))

But the plot its produces is not easy to determine the individual points/line

[Fangjun Jiang]

Should the start time be less than the stop time? Maybe it doesn't matter. Should horizontal lines be more suitable than vertical lines since they indicate time lapse? Anyway, see edit in my answer for both options.

[B_Richardson]

I'm going to try both and see which one is closer to what I'm trying to accomplish

Answer 4

[Paulo Silva]

stairs(B) %just one wild guess

[B_Richardson]

I tried it but the plot it produces is not easy to distinguish the lines

Answer 5

[B_Richardson]

Hey everybody, look try

 B =rand(10,2)
 stem(B)

this is kinda what I'm trying to do. Notice how it produces 10 lines. On each of those lines there are 2 points for a total of 20 points.

[Walter Roberson]

It wasn't clear from the above that you wanted both points to have the same x value; indeed, I had gathered from the earlier discussion that everything was to be spread out on a line (with gaps)

[B_Richardson]

oh, my apologies. It really doesnt matter what form its in (points, lines, dots, lol, etc)

And I prefer them spread across the same x value. But I'm just trying to visually display the 20 points with the connections 1,2 3,4 5,6 and so on to produce 10 distinct marks/lines/points.

[B_Richardson]

I think i may be confusing myself here (and everybody else), wouldnt I need to include a varilbe that contains the overall length of the video in the plot command somewhere? Or would that just be in the axis?