# How to convert rows to logical

6 vues (au cours des 30 derniers jours)
Simon Allosserie le 27 Oct 2022
I am filtering a set of values in a column vector in multiple steps. In the end, I get the row numbers of the values that should be kept, eg.:
A = 1:10;
%fitering happens
r = [2 7 8]; %the rows to keep
Now for subsequent calculations, I need A with only the filtered values, and 0's in the other values. At the moment I do it like this:
filter = ~min(logical(abs(A-r(:))),[],1)
filter = 1×10 logical array
0 1 0 0 0 0 1 1 0 0
Afiltered = A.*filter
Afiltered = 1×10
0 2 0 0 0 0 7 8 0 0
However this method isn't that elegant so I was wondering if there are some standard functions / quicker ways to get the same?
Due to the nature of the filters, it is not possible to work with masks that have the same length as A. r will always be shorter than A.
##### 0 commentairesAfficher -2 commentaires plus anciensMasquer -2 commentaires plus anciens

Connectez-vous pour commenter.

### Réponse acceptée

Star Strider le 27 Oct 2022
Why not just:
A = 1:10;
%fitering happens
r = [2 7 8]; %the rows to keep
Afiltered = zeros(size(A));
Afiltered(r) = A(r)
Afiltered = 1×10
0 2 0 0 0 0 7 8 0 0
.
##### 2 commentairesAfficher AucuneMasquer Aucune
Cris LaPierre le 28 Oct 2022
This is likely the better answer. Here, Afiltered is assigned the values in A. In my answer, it is assigned the row numbers. It only looks correct because, in this simplified example, the elements in A are the row numbers.
Simon Allosserie le 10 Nov 2022
Okay I will look into the differences between the two approaches and see which renders the results the fastest for the data that I use. Thanks for coming back to this!

Connectez-vous pour commenter.

### Plus de réponses (1)

Cris LaPierre le 27 Oct 2022
I'm not aware of a special function for this, but perhaps a more readable way would be this?
A = 1:10;
r = [2 7 8];
Afiltered=zeros(1,length(A));
Afiltered(r)=r
Afiltered = 1×10
0 2 0 0 0 0 7 8 0 0
##### 1 commentaireAfficher -1 commentaires plus anciensMasquer -1 commentaires plus anciens
Simon Allosserie le 27 Oct 2022
Yes this is indeed much more simple, I was making it way too complicated. Thanks for helping me out of my thinking rut!

Connectez-vous pour commenter.

### Catégories

En savoir plus sur Matched Filter and Ambiguity Function dans Help Center et File Exchange

R2019b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by