The thing is i have a matrix and when i use imagesc() it goes like this but my goal is this.
So my question is does any one know which plot is this or some one has document about this, thanks.
If you have two vectors r and theta that give the polar coordinates, or two matrices rGrid and thetaGrid that give the polar coordinates for each element of the data matrix, then code like this will work:
r=linspace(1,20,20);
theta=linspace(0,2*pi,20);
data = r'.*sin(2.*theta); % INSERT DATA HERE
[thetaGrid,rGrid]=meshgrid(theta,r); % Create coordinate grid if needed
[xGrid,yGrid]=pol2cart(thetaGrid,rGrid);
surf(xGrid,yGrid,data); % Plot data
view(2);
Just keep in mind that the rows of the data matrix need to correspond to different radii, and columns need to correspond to different values of theta. If it's flipped, then transpose the matrix before plotting:
data = data';
Also, if the data doesn't wrap around from 0 to 2*pi radians, then repeat the first value of theta as the last value, and repeat the first column of the data matrix as a new final column:
theta(end+1)=theta(1);
data=cat(2,data,data(:,1));
There is also a 3D Polar Plot function on the MATLAB file exchange, but I do not have any experience using it: 3D Polar Plot
Related
For example, I got 3 pairs of 1-D loglog curves and additionally their associated cartesian coordinate points (x,y,z) of one of their ends A, B and C over a mesh surface S (z is positive downwards and linear but coincides in direction with the log(y)-axis from the curves). Is it possible to respresent in a single figure such system of plots in matlab?
Moreover, obtain an interpolated slice from A,B and C?
The images from the question of user3281667 gives an insight of what we are trying to do here:
https://gis.stackexchange.com/questions/252939/interpolating-xyz-data-in-arcgis-3d-analyst
Thanks.
Kind of solved. First we need to know in which format is our data, this case scattered.
I concatenated a nx4 matrix with the preprocessed data A=[X Y Z C].
Then use the right tools, to plot use scatter3: scatter3(A(:,1), A(:,2), A(:,3),30, A(:,4), 'filled' )
Now to interpolate, fisrt generate a grid refinement with meshgrid: [Xm, Ym, Zm] = meshgrid(min(X):2:max(X), min(Y):2:max(Y), min(Z):2:max(Z)) next interpolate using griddata Cm = griddata(X,Y,Z,C,Xm,Ym,Zm);and last plot again.
figure
scatter3(Xm(:), Ym(:), Zm(:), 30, Cm(:), 'filled' )
Thanks to user7431005
I'm trying to create a 3D plot in Matlab of a structure element, Bstruct.scen_1. In this structure, each row is a year, each column is a distance, and the cell value is a population size (so for example, row 3, column 7 would yield the number of adults in year 3 at 7 km.) I want the X-axis to be the number of columns in Bstruct.scen_1, the Y-axis to be the actual value in the cell at (X,Z), and the Z-axis to be the number of rows in Bstruct.scen_1.
Conceptually, what I'd like to accomplish is:
plot3(Bstruct.scen_1(1:num_cols), Bstruct.scen_1(cellvalue), Bstruct.scen_1(1:num_rows))
I'm struggling with the syntax of structures and would really appreciate help in plotting both the elements and the dimensions of this structure. (I mostly code in R with 'tidy' data.) Thank you!
The value of a structure field can be any data type. It sounds like the scen_1 field contains a 2D matrix. The plot3 function expects an X, Y, and Z coordinate for each data point. In your case, if you're wanting to plot the value of the matrix at each 2D location, using the function surf (or mesh) might provide a good start:
% random data for demonstration
Bstruct.scen_1 = rand(20, 10);
figure;
surf(Bstruct.scen_1);
I am trying to read in a 2D data set into a matrix, plot the matrix, as well as plot the IFFT of the matrix. The data is 128x2 data set, with frequency in the first column (A) vs amplitude in the second column (B)
Unfortunately, plotting the matrix of the data is not plotting the correct waveform. Also, the IFFT seems to be incorrect as well.
waves = csvread('10cm.txt');
A = waves(:,1);
B = abs(waves(:,2));
Matrix = [A B];
waves_transform = abs(ifft2(waves));
figure, plot(waves);
figure, plot(waves_transform)
When I read in each column of the data and plot A vs B, the waveform of the data is correct but the ifft2 of the data is incorrect. I need to properly take the inverse Fourier transform of the two dimensional data that I have read in.
waves = csvread('10cm.txt');
A = waves(:,1);
B = abs(waves(:,2));
Matrix = [A B];
waves_transform = abs(ifft2(Matrix));
figure, plot(A,B);
figure, plot(waves_transform)
waves & waves_transform
Does anyone know why reading in the data and plotting it is different than reading in each of the columns and plotting it results in different graphs? Also, can anyone help me take the IFFT of the 2D data correctly?
10cm.txt DATA FILE HERE: http://pastebin.com/0t0TwVvC
According to MATLAB documentation, if you do plot(Y) and Y is a matrix, then the plot function plots the columns of Y versus their row number. The x-axis scale ranges from 1 to the number of rows in Y.
So, in your case you have to do:
plot(waves(:,1), waves(:,2))
Might I also suggest a free and IMO better numpy package for python
I have a 25000x3-matrix, with each row containing a x-, a y- and a z-value. Now I wanted to do a graphical plot out of these. But for using for example surf(Z) I have to use a mxn-matrix as Z with m equal the size of x and n equal the size of y. How can I reshape the matrix I have to the needed mxn-matrix? The problem is that my x- and y-values are no ints, but floats, so I assume that I have to do a interpolation first. Is that true? My data plotted with plot3 looks like:
The fact that your x- and y- values are not integers is not a problem at all. The real question is: are your (x,y) points forming a grid, or not ?
If your points are forming a grid, then you have to reshape your columns to form m-by-n arrays. You may need to sort your data according to the first, then second column and then use the reshape function.
If your points are not forming a grid, then you will have to make an interpolation. By chance the scatterinterpolant class can nicely help you in doing so.
As you can see, the data you are providing is neither given in a gridded way, nor is the point cloud clean. You could however try to do the following:
Project the point cloud onto the x-y plane
Triangulate those points
Give the points their original z-coordinate back.
Plot the surface using trisurf
Here is a MATLAB code that does this:
%// Generate some points P
[X,Y] = ndgrid(0:30);
P = [X(:), Y(:), X(:).^2+Y(:)];
%%// Here the actual computation starts
[~,I] = unique(P(:,1:2),'rows'); %// Remove points with duplicate (x,y)-coords
P = P(I,:);
T = delaunay(P(:,1),P(:,2)); %// Triangulate the 2D-projection
surface = triangulation(T, P(:,1), P(:,2), P(:,3)); %// Project back to 3D
trisurf(surface); %// Plot
You may want to remove stray points first, though.
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]')