# Find close points in two matrices of coordinates

2 vues (au cours des 30 derniers jours)
Adam Fitchett le 22 Sep 2022
Commenté : Adam Fitchett le 28 Sep 2022
I have two different length matrices of 3D coordinates. I want to find all the unique coordinates in one matrix that are within a certain Euclidean distance of any of the coordinates in the other matrix. What is the most efficient way to do this?
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### Réponse acceptée

Torsten le 22 Sep 2022
Modifié(e) : Torsten le 22 Sep 2022
Use "pdist2" to calculate the distances of the sites of the first set to the sites of the second set.
Check which rows of the distance matrix D have an entry <= dmax where dmax is your prescribed maximum distance.
These are the sites of the first set you want to determine.
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Torsten le 22 Sep 2022
Modifié(e) : Torsten le 22 Sep 2022
Works for me.
set1 = [0,1,4;
2 5 8];
set2 = [-1,3,6 ;...
4,2,7 ;...
-2 6 9];
dmax = 3;
distance_set1_set2 = pdist2(set1,set2)
distance_set1_set2 = 2×3
3.0000 5.0990 7.3485 4.1231 3.7417 4.2426
indices = any(distance_set1_set2 <= dmax,2)
indices = 2×1 logical array
1 0
set1(indices==1,:)
ans = 1×3
0 1 4
Adam Fitchett le 28 Sep 2022
This worked thanks, although it turned out to be very memory-hungry for my large matrices
Used 98% of the RAM on a workstation with 256 GB of RAM!

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