plotting a single vector out of a multidimensional array?

Hi,

I've got an M-file that calculates error data and stores it in a multidimensional array. 1st Dimension determines which dataset I refer to, 2nd dimension determines which sensor in a multi-sensor array the measurements are from, and the 3rd dimension is finally the calculated error at each point of the original signal.

I'm thus just using a multi-dimensional array as a way to store all of the error vectors in a single structure. But, when I try to plot a single error vector at given index values for the 1st and 2nd dimensions using the plot command, I get matlab errors:

>>plot(Xhat(1,3,:));

"Error using plot Data may not have more than 2 dimensions"

Why won't that work? I've specified a 1-dimensional set of data for it to plot, but it won't do it? How should I approach this differently?

Answer 1

[Cedric]

You have two singleton dimensions when you index Xhat(1,3,:). Look at the following:

 >> A = rand(2,3,4) ;

 >> v = A(1,2,:)
 v(:,:,1) =
    0.4168
 v(:,:,2) =
    0.9841
 v(:,:,3) =
    0.3395
 v(:,:,4) =
    0.4228

 >> size(v)
 ans =
     1     1     4

 >> v = squeeze(A(1,2,:))
 v =
    0.4168
    0.9841
    0.3395
    0.4228

 >> size(v)
 ans =
     4     1

If you don't index across datasets too often, I would recommend switching your dimensions, e.g having sensor x point x dataset. This would simplify the indexing and make it (much) more efficient if you have large datasets.

[Jeff]

Thanks!

[Cedric]

You're welcome! Please read the last note that I wrote maybe after you saw my answer.