grouping array based on similar row element
5 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Poulomi Ganguli
le 8 Jan 2020
Commenté : lim xiang
le 16 Juil 2020
Hello,
I have a matrix A:
123 1970 1 1 12
123 1971 1 1 120
123 1972 1 12 300
240 1970 1 10 40
240 1971 2 1 45
240 1972 3 34 56
230 1970 1 2 120
230 1971 2 3 320
230 1972 1 14 360
I wish to export 3 different matrices in a folder based on the common column element. This might be easy without a loop using an index operation. The resulting matrices
A =
123 1970 1 1 12
123 1971 1 1 120
123 1972 1 12 300
B =
240 1970 1 10 40
240 1971 2 1 45
240 1972 3 34 56
C =
230 1970 1 2 120
230 1971 2 3 320
230 1972 1 14 360
3 commentaires
Image Analyst
le 8 Jan 2020
It's pretty universal among experienced MATLAB users that that would be a bad idea.
See the FAQ.
Now, if you want ot do it in a loop
uniqueValues = unique(A(:, 1));
for k = 1 : length(uniqueValues)
thisValue = uniqueValues(k);
rowsWithThisValue = A(:, 1) == thisValue;
subArray = A(rowsWithThisValue, :)
% Now do something with the subArray
end
then that would be okay.
Réponse acceptée
Guillaume
le 8 Jan 2020
The easiest:
savelocation = 'C:\somewhere\somefolder';
fileformat = 'submatrices_%02d.txt';
group = findgroups(A(:, 1));
splitapply(@(subA, index) writematrix(subA, fullfile(savelocation, sprintf(fileformat, index(1)))), A, group, group); %passing group twice so we get it in the anonymous function to use as file number
3 commentaires
Guillaume
le 9 Jan 2020
Or simpler:
splitapply(@(subA) writematrix(subA, fullfile(Save_Location, sprintf('%d.txt', subA(1))), 'Delimiter', ' '), A, group);
Plus de réponses (0)
Voir également
Catégories
En savoir plus sur Matrix Indexing dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!