grouping rows and store is separate matrix

hi all,

in the script below I have p which is (m,3) vectors matrix, Itried to group this matrix according to z-value in L1 vector, so in case L1 is (0,0-2), rows of matrix p should be filtered according to z=-2, and each filtered rows have to be seperatly stored. I failed to do this pls help

clc

clear

close all

format long

x=[];

y=[];

z=[];

for L=-2:0.5:2

for r=0:.5:2

for theta=0:45:360;

x=[x;r*cos(theta*pi/180)];

y=[y;r*sin(theta*pi/180)];

z=[z,L];

L1=[x-x,x-x,z'];

end

end

end

lx=L1(:,1);ly=L1(:,2);lz=L1(:,3);

z=z';

p=[x,y,z];

a = cell(length(L1),1);

for ii = 1:length(L1);

a{ii} = p(p(:,3) == L1(ii,3),:);

end

celldisp(a)

Answer 1

[Sai Gudlur]

Hello Oday,

I couldn't understand you question completely but to to certain degree i could.

x=[x;r*cos(theta*pi/180)];

y=[y;r*sin(theta*pi/180)];

z=[z,L];

Do not think this is necessary. if i were u would do it this way.

x=[];

y=[];

z=[];

L = -2:0.5:2;

r=(0:.5:2)';

theta=0:45:360;

x = (r.*cos(theta*pi/180));

L1=[x-x,x-x,z'];

Again this part are you trying subtract elements in the 2nd column of matrix x from the 1st Column?

A little more detail might help.

[Oday Shahadh]

ok thanks to be patient with me

if I have two matrices A(5,3), B(20,3), A(x1,y1,z1),B(x2,y2,z2)

so for instance if A(1,2,3), I need to group out all rows from B that have the same z-value in A, which is (3)

[Oday Shahadh]

L1 is just to creat vector of (0,0,z), have the same length of x &y

[Oday Shahadh]

in the attched image you can see multi level set of points, I need to cross product between each center point of each level with its related points at the same level which the surley have the same z-value, so it need to group out each set of points then make the cross product

[Sai Gudlur]

I do not know how much would this help but try.

"ismember" or if i were you would try "intersect". This would return the values that have the same A&B "z" value. and then you could proceed to do that operation.

Another possibility is you could use "Unique" and find the ones that aren't the same and later use the common values of A & B.

[Oday Shahadh]

your first accepted answer :)