# Sorting cell array based on distance

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Pelajar UM on 18 Oct 2021
Commented: KSSV on 18 Oct 2021
I have two cell arrays that contain information about the x,y,z coordinates for points in space. These data are random and do not necessarily follow any sequence.
Example of data1:
-512.7269 -223.8000 -256.1018
-509.1519 -223.8000 -263.4274
-512.9410 -223.8000 -256.3643
-508.8008 -223.8000 -263.5808
-521.0831 -223.8000 -263.1835
-520.0226 -223.8000 -259.8741
-505.0888 -223.8000 -251.5124
-504.7663 -223.8000 -251.4452
Example of data2:
-500.2925 -178.0828 -260.5501
-500.3713 -177.7340 -259.0459
-500.4465 -177.1616 -257.6118
-500.5162 -176.3785 -256.2803
-500.5790 -175.4029 -255.0823
-500.6334 -174.2572 -254.0454
-500.6780 -172.9680 -253.1935
-500.7120 -171.5645 -252.5458
I am trying to sort the data so that the nearest points in space appear in the same sequence of rows.
This is how the code looks like so far. It calculates the minimum distance for combination of every 2 points and then sort this distance in an ascending fashion. What is missing is the part that updates 'data1' to follow the same sequence.
data1 = importdata ('nodes.txt')
Xi = data1(:,1);
Yi = data1(:,2);
Zi = data1(:,3);
data2 = importdata ('TT_angleBlock_nodes.csv')
Xt = data2(:,1);
Yt = data2(:,2);
Zt = data2(:,3);
input = [Xi,Yi,Zi];
output= [Xt,Yt,Zt];
for row = 1 : 1:row
deltaX = output(row,1) - input(:,1);
deltaY = output(row,2) - input(:,2);
deltaZ = output(row,3) - input(:,3);
% Pythagorean Theorem
distances = sqrt(deltaX .^2 + deltaY .^ 2 + deltaZ .^ 2);
minDistance(row) = min(distances);
Dist = sort (minDistance);
end

KSSV on 18 Oct 2021
Read about knnsearch. This will give you the nearest points from a set points for a given point. This will work for you.
KSSV on 18 Oct 2021
Yes....you got it.