operations on structer under specific conditions ?

if there is a structure (S) for 10 nodes. the three fields of the structure are (xd , yd and ID) where,,

S.xd ==> X-dimension , S.yd ==> Y_dimension , S.ID ==> node's order or its ID , S.E ==> Energy

the distance between two nodes i and j equal D(i,j)= sqrt((S(i).xd-S(j).xd)^2+(S(i).yd-S(j).yd)^2).

i want to compare the distance between all nodes, hence if the distance between two nodes is less than specific value (do), we keep the higher energy nodes and neglect the other.

at the end we get the structure of the new higher energy nodes

Answer 1

[KSSV]

You can find the distance between one node to other the other nodes using the following lines:

clc; clear all ;
N = 10 ;
for i = 1:N
    s(i).id = i ;
    s(i).x = rand(1,1) ;
    s(i).y = rand(1,1) ;
end
%%distance between i'th node and other nodes 
for i = 1:N
    data = repmat([s(i).x s(i).y],[N,1])-[[s.x]' [s.y]'] ;
    dist = sqrt(data(:,1).^2+data(:,2).^2);
    %%Do what you want
end

[Abdelwahab Fawzy]

Getting the matrix of the distance between nodes isn't my problem

for i=1:n

    for j=1:n

        D(i,j)=sqrt((S(i).xd-S(j).xd)^2+(S(i).yd-S(j).yd)^2);
    end 
end

now i'm interested in finding the nodes which the intersection distance between them < doo

D(D<doo) to compare their energy, hence i can keep the higher energy node and neglect the smaller energy one

Answer 2

[KSSV]

That i snot a big deal...

clc; clear all ;
N = 10 ;
for i = 1:N
    s(i).id = i ;
    s(i).x = rand(1,1) ;
    s(i).y = rand(1,1) ;
end
%%distance between i'th node and other nodes 
for i = 1:N
    data = repmat([s(i).x s(i).y],[N,1])-[[s.x]' [s.y]'] ;
    dist = sqrt(data(:,1).^2+data(:,2).^2);
    %%Do what you want
    % get the indices whose distance is less then 0.5
    idx = find(dist < 0.5) ;
    nodes = [[s(idx).x]' [s(idx).y]']
end

Answer 3

[Stephen23]

Rather than writing slow and ugly loops, you could simply use bsxfun:

do = 0.9;
S = struct(...
    'xd',num2cell(rand(1,10)),...
    'yd',num2cell(rand(1,10)),...
    'E', num2cell(rand(1,10)));
%
hyp = bsxfun(@hypot,[S.xd].',[S.yd]);
idx = hyp<do
...etc