How do I make different groups within a matrix?
9 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Jaime Castiblanques
le 12 Mar 2021
Commenté : Jaime Castiblanques
le 15 Mar 2021
I have a 2904x3 matrix where each column represents the x, y and z coordinates of some vectors. Some of these vectors have the same z-coordinate and I need to group those together. Any ideas?
3 commentaires
Adam Danz
le 12 Mar 2021
Extending Mathieu NOE's suggestion, the 3rd output to unique is a grouping variable but you should use the stable flag to ensure that the grouping values correspond to each element of the vector.
% xyz is nx3 matrix of [x,y,z] values
[~,~,zgroup] = unique(xyz(:,3));
Alternatively, if you just want to sort the matrix according to the z column,
xyzSort = sortrows(xyz,3);
Réponse acceptée
Veronica Taurino
le 12 Mar 2021
Modifié(e) : Veronica Taurino
le 12 Mar 2021
How do you need to get arrays associated?
Try this:
clear all
close all
x= (50)*rand(50,1);
y= (50)*rand(50,1);
z= (50)*rand(50,1);
% I create 4 equal z coordinates:
z(12)=z(23);
z(34)=z(23);
z(1)=z(23);
z(45)=z(23);
z(23)
% Put all together
AA= [x,y,z];
% Look for index
[~, ind] = unique(AA(:, 3), 'rows');
% DUPLICATE INDEX
duplicate_index = setdiff(1:size(AA, 1), ind) % This finds the indexes of duplicates
% duplicate values
duplicate_value = AA(duplicate_index, :) % This extracts the arrays with duplicates
results:
z(23) =
12.6859 % the Z value I imposed
duplicate_index = % indexes of duplicates the script finds
12 23 34 45
duplicate_value = % array with same Z the script finds
19.6717 40.5660 12.6859
47.5017 3.6415 12.6859
11.9746 35.4336 12.6859
38.4967 19.0424 12.6859
6 commentaires
Veronica Taurino
le 15 Mar 2021
I think it may happen what I told you in the comment above, with dedicated link. Did you check it?
Plus de réponses (0)
Voir également
Catégories
En savoir plus sur Matrix Indexing dans Help Center et File Exchange
Produits
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!