Find/return value from each row in a big matrix that corresponds with a condition/value
5 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Dear All Community members,
I have a big matrix ("A") and want to return values from an array "x" for each row when a condition/value is met in matrix A.
A simplified example is given below;
A=[0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 1 1 1 1 1 1 1 1 1; 0 0.15 0.30 0.45 0.60 0.75 0.90 1 1 1 1 1 1 1 1 1 1 1 1 1 1; 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1];
x=[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20];
Condition, c=0.9
I want to find in matrix "A" the first value that meets the condition in "c" and return the corresponding values from "x". I.e. the resulting vector shall be= 9,6,18.
Any help or tips is deeply appreciated.
Thanks in advance
0 commentaires
Réponses (4)
Cris LaPierre
le 10 Août 2020
Is the order of the resulting vector important?
You can just do a normal equality comparison, then use any to create a logical vector displaying if the corresponding column contains at least one true value.
A=[0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 1 1 1 1 1 1 1 1 1; 0 0.15 0.30 0.45 0.60 0.75 0.90 1 1 1 1 1 1 1 1 1 1 1 1 1 1; 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1];
x=[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20];
c=0.9;
D=A==c;
ind = any(D,1);
x(ind)
ans = 1×3
6 9 18
5 commentaires
Cris LaPierre
le 10 Août 2020
Modifié(e) : Cris LaPierre
le 10 Août 2020
A=[0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 1 1 1 1 1 1 1 1 1;
0 0.15 0.30 0.45 0.60 0.75 0.90 1 1 1 1 1 1 1 1 1 1 1 1 1 1;
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1];
x=[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20];
c=0.9;
D=A-c;
% You only want greater than or equal to, so set everything less than to a large positive value
D(D<0)=999;
[~,ind] = min(D,[],2)
x(ind)
Bruno Luong
le 10 Août 2020
Modifié(e) : Bruno Luong
le 10 Août 2020
"Let me specify, I only want the first time the value appears in each row and if the value dont appear I want closest value."
Then use MIN rather than FIND, and no need to fix emperically the tolerance.
c = 0.9;
[~,col] = min(abs(A-c),[],2);
x(col)
0 commentaires
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!