# Plotting Matrix points

5 views (last 30 days)
B_Richardson on 19 Jul 2011
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!
B_Richardson on 20 Jul 2011
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 on 20 Jul 2011
Your figure is almost done with the Horizontal lines solution I provided.

Walter Roberson on 19 Jul 2011
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.
B_Richardson on 19 Jul 2011
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 on 20 Jul 2011
plot(repmat(ConstantX, 1, size(B,1)), B.', 'b-o')

Sean de Wolski on 19 Jul 2011
line(B(:,1),B(:,2))
maybe?
What do you mean by start of first and end?
B_Richardson on 19 Jul 2011
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.

Fangjun Jiang on 19 Jul 2011
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');
Fangjun Jiang on 20 Jul 2011
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 on 20 Jul 2011
I'm going to try both and see which one is closer to what I'm trying to accomplish

Paulo Silva on 19 Jul 2011
stairs(B) %just one wild guess
B_Richardson on 19 Jul 2011
I tried it but the plot it produces is not easy to distinguish the lines

B_Richardson on 19 Jul 2011
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.
##### 3 CommentsShow 1 older commentHide 1 older comment
B_Richardson on 19 Jul 2011
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 on 19 Jul 2011
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?