Plotting a line between two points

Hi,

I am encountering a problem trying to plot a line between two points (x1, y1; x2, y2). I have a dataset with alternating columns of x- and y-coordinate data (e.g. in a 10 by 10 matrix), and I added two new columns (e.g. columns 11 and 12) whereby column 11 is the mean x-coordinate of columns 1, 3, 5, ... and column 12 is the mean y-coordinate of columns 2, 4, 6,...

A(:,11)=mean(A(:,1:2:9),2);
A(:,12)=mean(A(:,2:2:10),2);

I want to plot a line between each point and the average so I use this as an example:

plot([A(1,1) A(1,11)],[A(1,2) A(1,12)])

This should plot a line between the first x- and y-coordinate and the mean x- and y-coordinate of the first row. However, the error message that I am getting is

"Data must be a single matrix Y or a list of pairs X,Y"

The frustrating thing is I tried it with randomly generated integers e.g.

A=randi(100,10,10)

and it works, but on my dataset it doesn't. I also noticed that the numeric format of the two additional columns I created are different, and I wonder if that plays a part.

Any help is appreciated.

Thank you.

Answer 1

[Star Strider]

You may need to transpose the (10x2) matrices for each column in order to plot them as you want.

Try this (for the first column of ‘A’):

figure
plot([A(:,1) A(:,11)]', [A(:,1) A(:,12)]')

[Benedict Low]

Thank you @Star Strider. I took out columns 11 and 12 and did a repmat to make the two matrices the same size. Then transposing the data as you advised worked.

[Star Strider]

As always, my pleasure.

The plot function works in mysterious ways.