MATLAB: Clustering data into specific range

classificationclustering

Hi,

I have a wind speed data that contain information of Latitude:Longitude:Wind speed, of a specific area. Right now, I want to classify the wind speed value into 3 clasess which are low, medium and high.

This is my data example

Latitude Longitude Wind speed

0.0000000e+00 9.5000000e+01 3.6036667e+00

0.0000000e+00 9.5250000e+01 3.5781667e+00

0.0000000e+00 9.5500000e+01 3.5515000e+00

0.0000000e+00 9.5750000e+01 3.5359167e+00

0.0000000e+00 9.6000000e+01 3.5348333e+00

0.0000000e+00 9.6250000e+01 3.5368333e+00

0.0000000e+00 9.6500000e+01 3.5077500e+00

0.0000000e+00 9.6750000e+01 3.4358333e+00

0.0000000e+00 9.7000000e+01 3.3370000e+00

0.0000000e+00 9.7250000e+01 3.2308333e+00

0.0000000e+00 9.7500000e+01 3.1323333e+00

0.0000000e+00 9.7750000e+01 3.0404167e+00

0.0000000e+00 9.8000000e+01 2.9537500e+00

0.0000000e+00 9.8250000e+01 2.8655833e+00

0.0000000e+00 9.8500000e+01 2.7736667e+00

0.0000000e+00 9.8750000e+01 2.6754167e+00

0.0000000e+00 9.9000000e+01 2.5668333e+00

0.0000000e+00 9.9250000e+01 2.4494167e+00

0.0000000e+00 9.9500000e+01 2.3389167e+00

I want to classify the data into low wind speed (0-1.9 m/s), medium wind speed (2-4.9 m/s) and high wind speed (5-9 m/s). Can anybody share to me and help me to find solution for my problem ?.

Best Answer

check out the data type categorical

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MATLAB: Stl export for geometry from pointcloud/array

I should start this answer with 'I have no idea what I'm doing here'. I found your question interesting and have had a go at it with a combination of googling and experimentation. As such, this may be a terrible way to proceed but I seem to have got somewhere

The first complication is that there are at least two stlwrite functions:

Official MATALB one: https://uk.mathworks.com/help/matlab/ref/stlwrite.html
One on the FEX: https://uk.mathworks.com/matlabcentral/fileexchange/20922-stlwrite-write-ascii-or-binary-stl-files

. I think that your forum posts were referring to the FEX version which is older. For what follows, I use the FEX version

d = [0 1];
[x,y,z] = meshgrid(d,d,d); % a cube
x = [x(:);0];
y = [y(:);0];
z = [z(:);0];
stlwrite('Quader.stl',boundary(x,y,z),[x,y,z],'mode','ascii');

I used a free stl viewer to look at the result and the wireframe returned was

I chose ASCII output so we can look at it. Probably want to use binary output (the default) for big files. The contents of the file are

solid Created by stlwrite.m 13-Oct-2020 16:32:19
facet normal 0.0000000E+00 0.0000000E+00 -1.0000000E+00
outer loop
vertex 0.0000000E+00 0.0000000E+00 0.0000000E+00
vertex 0.0000000E+00 1.0000000E+00 0.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal 0.0000000E+00 -1.0000000E+00 0.0000000E+00
outer loop
vertex 0.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 0.0000000E+00 0.0000000E+00 0.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal -1.0000000E+00 0.0000000E+00 0.0000000E+00
outer loop
vertex 0.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 0.0000000E+00 1.0000000E+00 0.0000000E+00
vertex 0.0000000E+00 0.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal -1.0000000E+00 -0.0000000E+00 -0.0000000E+00
outer loop
vertex 0.0000000E+00 1.0000000E+00 1.0000000E+00
vertex 0.0000000E+00 1.0000000E+00 0.0000000E+00
vertex 0.0000000E+00 0.0000000E+00 1.0000000E+00
endloop
endfacet
facet normal -0.0000000E+00 -1.0000000E+00 -0.0000000E+00
outer loop
vertex 1.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 0.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal 0.0000000E+00 0.0000000E+00 1.0000000E+00
outer loop
vertex 0.0000000E+00 1.0000000E+00 1.0000000E+00
vertex 0.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 1.0000000E+00
endloop
endfacet
facet normal 1.0000000E+00 0.0000000E+00 0.0000000E+00
outer loop
vertex 1.0000000E+00 1.0000000E+00 0.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal 0.0000000E+00 0.0000000E+00 -1.0000000E+00
outer loop
vertex 0.0000000E+00 1.0000000E+00 0.0000000E+00
vertex 1.0000000E+00 1.0000000E+00 0.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal 0.0000000E+00 1.0000000E+00 0.0000000E+00
outer loop
vertex 0.0000000E+00 1.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 1.0000000E+00 0.0000000E+00
vertex 0.0000000E+00 1.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal 1.0000000E+00 0.0000000E+00 0.0000000E+00
outer loop
vertex 1.0000000E+00 1.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 1.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal -0.0000000E+00 1.0000000E+00 0.0000000E+00
outer loop
vertex 0.0000000E+00 1.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 1.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 1.0000000E+00 0.0000000E+00
endloop
endfacet
facet normal -0.0000000E+00 0.0000000E+00 1.0000000E+00
outer loop
vertex 0.0000000E+00 1.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 0.0000000E+00 1.0000000E+00
vertex 1.0000000E+00 1.0000000E+00 1.0000000E+00
endloop
endfacet
endsolid Created by stlwrite.m 13-Oct-2020 16:32:19

MATLAB: Get in Order respond when using “eig” command

To sort the eigenvalues to be increasing in magnitude, use the following:

[U, d] = eig(k, m, 'vector');
[d, ind] = sort(d);
U = U(:, ind);

The eig function doesn't sort the eigenvalues it returns, for two reasons:

1) This is not needed for many applications, and would slow down the computation time for these cases. 2) For non-symmetric eigenvalue problems, the eigenvalues are complex, and none of the sorting methods for complex values are very satisfactory.

For symmetric problems (for the generalized case, this means both matrices are symmetric, and the second matrix is also positive definite), the eigenvalues are typically returned in ascending order by eig, but this is not a guarantee.

Best Answer

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MATLAB: Get in Order respond when using “eig” command

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