how to get a new array with some values from an old array
24 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Hi, I'm a matlab beginner, I have a little problem with creating a new matrix. I have a matrix "A" of dimensions (1840x44), I am attaching a photo of a part of it.
I need to get a matrix "B" that has the values of matrix "A" that are greater than 20. I tried doing B = (A>=20), but it only returns the positions (I need the value). Many thanks to whoever can help me with this little problem.
0 commentaires
Réponse acceptée
Voss
le 26 Nov 2022
B = (A >= 20) % same as B = A >= 20, i.e., without parentheses
makes B a matrix of logicals, the same size as A; the elements of B where A is greater than or equal to 20 are true; other elements of B are false.
To get the values of A that are >= 20, you can say:
B = A(A >= 20)
but it won't be a matrix, it will be a column vector. The elements of B will be in the same (column-major) order as they are in A.
Example:
A = [1 3.2 5.4]+[0;1;2;3]
B = A(A >= 4)
Alternatively, if you want B to be a matrix the same size as A, containing the elements of A that are >= 20 located at the same locations where they are in A and say zeros or NaNs everywhere else, you can do something like this:
B = NaN(size(A)); % or B = zeros(size(A)); % for instance
idx = A >= 4;
B(idx) = A(idx)
2 commentaires
Plus de réponses (0)
Voir également
Catégories
En savoir plus sur Creating and Concatenating Matrices 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!