I have multiple vectors of varying lengths that I would like to plot next to each other in 3D space in Matlab.
As an example:
Say I have three vectors:
X is a 5x2 vector,
Y is a 10x2 vector and
Z is a 15x2 vector.
Each element of every vector has the format:
x value, y value
but the x values of the various vectors do not match.
I would like to plot these vectors in 3D space, next to each other. The reason why I don't want to plot them using "hold" is because most of the data have the same values, but I would like to see how many of the plots have the same value at a specific time.
I hope my questions makes sense. Please just ask if anyone is unsure.
I think you are looking for the function ribbon.
Documentation: http://www.mathworks.fr/help/techdoc/ref/ribbon.html
EDIT:
if your x's do not have the same length, you can combine it with interp1 as follow:
x1=0:0.1:1;
x2=0:0.02:1.5;
y1=x1.^2;
y2=sqrt(x2);
y2=interp1(x2,y2,x1);
ribbon(x1',[y1;y2]')
Related
I have an n-dimensional matrix, funtointerpolate, and I wish to perform one dimensional interpolation along one of its axes (let's call it axis m). In Python, interpolate functions such as interp1d allow one to specify the axis of interpolation. In MATLAB, I cannot see an obvious way to do this using interp1 or any other built-in interpolate functions. Ideally, the function would look something like
interpolatedfun = interp1(funtointerpolate,oldpoints,newpoints,axis = m)
An obvious way to get around this is to loop over all the other axes in funtointerpolate, but this is rather cumbersome. The motivation for interpolation is that the data in funtointerpolate is evaluated along a non-uniform grid along the m axis. I need it to be uniform along m. Mathematically, suppose I have some tensorial object
A_{ijk}
which is evaluated along a non-uniform grid along the j index. Then, I wish to find a new A such that the jth index consists of values evaluated on a uniform grid. I know the new uniform grid for the jth index, newpoints, and the old grid oldpoints.
You can use the interpn function for this purpose:
newV = interpn(oldAx1, ..., oldAxM, ..., oldAxN, oldV, ...
oldAx1, ..., newAxM, ..., oldAxN);
where V is your output.
(Of course the above is pseudo-code, but it should nicely illustrate the way to solve your problem.)
I have a 100 x 100 matrix and i have to use plot3 in MATLAB environment to graph this data. I tried plot3(matrix name) but I faced this error "not enough input arguments". I think plot3 needs 3 input arguments, but I only have this matrix of data. could anyone help me to solve this problem? Is there any alternative for plot3 when we don't have enough arguments?
I need a graph like this:
I think you want to plot the values in a figure as a sort of surface element. What you can do then is:
[X,Y] = size(matrix);
figure;
surface(1:X,1:Y,matrix);
What this does is that it creates a vector for both X and Y indices, as possible in surface. The X and Y indices are obtained by setting them as integers from 1:size, so basically you assign the location of each matrix element to an index.
Note that you can strictly speaking use surface(matrix) as well, but the former approach allows you to use custom indexing, as long as the lengths of the vectors X and Y are the same as the size of your matrix.
For the waterfall use:
figure;
waterfall(matrix);
Sample code:
A=rand(100);
figure;
waterfall(1:100,1:100,A);
Gives:
where you can play around with the name-value pairs, see the documentation on that.
I think what you need is mesh or surf instead of plot3.
plot3 draws a line in 3d-space, so it will need three vectors of the same length (one for each dimension).
When you have a matrix, one reasonable way of displaying it is as a surface in 3d space, which is done by the functions mesh and surf.
Try it out! I hope i helps!
I have a 3d matrix of 100x100x100. Each point of that matrix has assigned a value that corresponds to a certain signal strength. If I plot all the points the result is incomprehensible and requires horsepower to compute, due to the large amount of points that are painted.
The next picture examplify the problem (in that case the matrix was 50x50x50 for reducing the computation time):
[x,y,z] = meshgrid(1:50,1:50,1:50);
scatter3(x(:),y(:),z(:),5,strength(:),'filled')
I would like to plot only the highest values (for example, the top 10). How can I do it?
One simple solution that came up in my mind is to asign "nan" to the values higher than the treshold.
Even the results are nice I think that it must be a most elegant solution to fix it.
Reshape it into an nx1 vector. Sort that vector and take the first ten values.
num_of_rows = size(M,1)
V = reshape(M,num_of_rows,1);
sorted_V = sort(V,'descend');
ind = sorted_V(1:10)
I am assuming that M is your 3D matrix. This will give you your top ten values in your matrix and the respective index. The you can use ind2sub() to get the x,y,z.
Inside a MATLAB function I have built a matrix A, whose dimensions M and N are set as parameters of the function. I would like to plot all the columns of this matrix, given a vector of indices B with length M. Hence, I use these lines:
figure
plot(B,A)
I specified figure as the MATLAB function returns more different plots.
My problem is that the program plots just two columns of the matrix with different colours (blue and violet). Where is my mistake?
Thank you for your attention.
go for
plot(repmat(B,1,N),A);
or
plot(repmat(B,N,1),A);
(depending on your rows/columns). You need to have same size matrices in plot.
Moreover, if B are just consecutive indexes, you may want to consider Plot(A) (or Plot(A')).
I noticed that there was an error which caused the overlap of the different curves, so the way which I used to plot the colums of a matrix is valid. However, the method proposed by Acorbe is a possibility, too.
I need to make a 3D surface where colour will represent the fourth variable. I know "surf" is SIMILAR to what I need, but that's not quite it. Basically, I have the following variables:
t = [1:m]
y = [1:n]
a = [1:o]
These should be the three Cartesian corodinate axes.
I also have a variable S that is of dimensions m x n x o, and is basically the amplitude, a function of the previous three variables (i.e. S = f(t,y,a)). I want this to be represented by colour.
So to summarize, I need a graph of the form (t,y,a,S), where the first three variables are vectors of unequal sizes and the final variable is a multidimensional array whose dimensions are determined by the first three.
Thanks in advance.
SCATTER3 requires x, y and z and other grouping arguments to be equally-sized Nx1 vectors for a single series or NxM matrices for M series.
You have full space 3D data. To make equally-sized coordinate vectors use MESHGRID (or NDGRID) function:
[X, Y, Z] = meshgrid(t, y, a);
Then you can use SCATTER3:
scatter3( X(:), Y(:), Z(:), [], S(:) )
The problem is since it's full space data scatter3 will not be helpful specially if you have a lot of points.
You can probably filter your S variable (something like idx = S > 0), then you can plot filtered data.
If you really need to visualize all the data, look at Volume visualization in MATLAB documentation. I can recommend SLICE function, for example.
EDIT
Here is an example of full 3D space scatter plot for small vectors (m, n, o equal to 5) with S = rand([m,n,o]); scatter3( X(:), Y(:), Z(:), [], S(:), 'filled' )
EDIT 2
From your comments to the other answer I found that you have 32x76050x4 matrix. You can actually plot 2D slice one at a time. you can do it in 2D with IMAGESC function, or in 3D with SLICE function.
Try:
imagesc(S(:,:,k))
where k is a number from 1 to 4 for the 3rd dimension.
Or try
slice(S, [], [], 1:size(S,3))
shading flat
Maybe this user-created plotting routine can help.
Screnshot from the linked page:
I've always used scatter3 for coloring/sizing pixels in 3d space. I believe the signature is:
scatter3(x,y,z, size, color)
The size and color can be scalar or vector of length equal to the coordinates. I usually use either the color or the size to reflect the fourth attribute, depending on what I'm showing. I don't have Matlab on this machine, so forgive me if my memory isn't completely accurate on the usage. "help scatter3" should describe it much better.