Effacer les filtres
Effacer les filtres

Removing adjacent duplicate numbers in rows of a matrix

2 vues (au cours des 30 derniers jours)
AA
AA le 21 Juin 2019
Commenté : infinity le 23 Juin 2019
Hi,
assume the following matrix format:
xx=[1 2 3 3 4 4; 1 1 2 2 3 3 ; 5 5 5 3 3 2]
I want to remove the adjacent duplicate numbers in each row of this matrix so I get the following output:
result=[1 2 3 4; 1 2 3 ; 5 3 2]
Help would be very much appreciated with a formula. Thanks.

Connectez-vous pour répondre à cette question.

Réponses (2)

infinity
infinity le 21 Juin 2019
Hello,
In your problem, you may get error since your result is not a matrix (number of colume of the first row is different with other rows).
So, you result should be a cell like this
clear
xx=[1 2 3 3 4 4; 1 1 2 2 3 3 ; 5 5 5 3 3 2]
for i = 1:size(xx,1)
yy{i} = unique(xx(i,:));
end
  12 commentaires
Afficher 10 commentaires plus anciens
AA
AA le 22 Juin 2019
Modifié(e) : AA le 22 Juin 2019
Hi,
somehow I see an error when I modify the xx and increase the set of numbers. Adjacent numbers can repeat like 3 or 2 or 5 but they are not displayed in the output.
clear
xx=[1 2 3 3 4 4 3; 1 1 2 2 3 3 2; 5 5 5 3 3 2 5]
%yy = zeros(size(xx));
yy=NaN(size(xx))
for row = 1:size(xx,1)
temp = unique(xx(row,:),'stable');
yy(row,1:length(temp)) = temp;
end
The last digit 3 or 2 or 5 is not shown in the output. Instead i get
1 2 3 4 NaN NaN NaN
1 2 3 NaN NaN NaN NaN
5 3 2 NaN NaN NaN NaN
but I should get
1 2 3 4 3 NaN NaN
1 2 3 2 NaN NaN NaN
5 3 2 5 NaN NaN NaN
How can I modify the formula?
infinity
infinity le 23 Juin 2019
Hello,
You can modify the code like this
clear
% xx=[1 2 3 3 4 4; 1 1 2 2 3 3 ; 5 5 5 3 3 2]
% xx=[1 2 3 3 4 4; 1 1 2 2 3 3 ; 5 4 5 3 3 2]
xx=[1 2 3 3 4 4 3; 1 1 2 2 3 3 2; 5 5 5 3 3 2 5]
% xx=[1 2 3 3 4 4 3 3; 1 1 2 2 3 3 2 3; 5 5 5 3 3 2 5 5]
n = size(xx,2);
% yy = 0*xx;
yy=NaN(size(xx));
for i = 1:size(xx,1)
[temp,ia,ib] = unique(xx(i,:),'stable');
f = diff(ib)~=0;
idx = [find(f);length(ib)];
% yy(i,1:length(temp)) = temp;
yy(i,1:length(idx)) = xx(i,idx);
end
yy

Connectez-vous pour commenter.

Rik
Rik le 22 Juin 2019
You can use diff to find any repeats and remove them. The compare to eps is to avoid strange things happening once you put in decimal numbers, which can lead to rounding errors, which is why exp(log(3))==3 returns false.
xx=[1 2 3 3 4 4 3; 1 1 2 2 3 3 2; 5 5 5 3 3 2 5];
yy=NaN(size(xx));
for row = 1:size(xx,1)
temp = xx(row,:);
%keep values that are different from the one before
%L=[true diff(temp)~=0];%line below is safe for float rounding
L=[true abs(diff(temp))>=(2*eps)];
yy(row,1:sum(L)) = temp(L);
end
%remove trailing NaN cols:
while all(isnan(yy(:,end)))
yy(:,end)=[];
end
disp(yy)

Catégories

En savoir plus sur Creating and Concatenating Matrices dans Help Center et File Exchange

Tags

Community Treasure Hunt

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

Start Hunting!

Translated by