How to remove repeating elements from an array

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NS
NS 2011-9-25
评论： Life is Wonderful 2020-4-12
Hi Guys,
I have two matrices X and Y of the same size. Each element in Y has a corresponding element in X. There are some repeating values in X (and correspondingly in Y as well). Is there any way to remove these elements from the matrices.
Thanks, NS
  2 个评论
Hesham Hendy
Hesham Hendy 2014-11-22
If I want to keep one value of repeated values without sorting, what can I do ???

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采纳的回答

UJJWAL
UJJWAL 2011-9-26
Hi NS,
Ok. Now I understand what you want. ok. There is a way to do this. Take a look at the code below :
a = randi(10,[1,20]);
[b,m1,n1] = unique(a,'first');
[c1,d1] =sort(m1);
b = b(d1);
In this way your problem is solved. similarly you can also do so for the other matrix. Hope this helps...
Happy to help
UJJWAL
  2 个评论
Andrei Bobrov
Andrei Bobrov 2011-9-26
[a b] = unique([X;Y]','rows','first');
xyb = sortrows([a b],3)';
X = xyb(1,:);
Y = xyb(2,:);
NS
NS 2011-9-26
Thanks. I figured it that day itself. :)

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更多回答（4 个）

UJJWAL
UJJWAL 2011-9-25
Use the unique function. Take the following example :-
a = randi(10,[1,20]) will display a 1 by 20 matrix of pseudorandom integers with uniform distribution in the range 1:10 . Obviously there will be repeated elements in the matrix. Suppose now you create a second matrix p = sin(a). So there is a mapping defined. Now type unique(a). It will give you only the unique values in a that is it will not display repeated values of the same element. Now type unique(p) : It will similarly display the unique values in p.
Hope it resolves your doubt
Best Wishes
Ujjwal
  2 个评论
Jan
Jan 2011-9-25
If you want to remove elements on the same positions in both matrices, you can use the 2nd and 3th output of unique. See "help unique".
NS
NS 2011-9-25
Hi Ujjwal,
I dont want the order of the elements to be rearranged. When I use unique, the elements are arranged in an ascending order.
Eg. if X=[0 13 18 22 22] and Y=[0 1 -1 3 3]
I want my output to be as X=[0 13 18 22] and Y=[0 1 -1 3]
How do I do that

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Fangjun Jiang
Fangjun Jiang 2011-9-26
For duplicated x-y pairs, if you want to keep the last one:
X=[0 13 22 18 22 22 10];
Y=[0 1 3 -1 3 3 -1];
A=[X;Y]';
[UniXY,Index]=unique(A,'rows');
DupIndex=setdiff(1:size(A,1),Index);
A(DupIndex,:)=[];
X=A(:,1)'
Y=A(:,2)'
X =
0 13 18 22 10
Y =
0 1 -1 3 -1
If you want to keep the first one, use:
[UniXY,Index]=unique(A,'rows','first');
SIVAKUMAR KARURNKARAN
function B=adjacentmat(n,e) R=combntns(1:n,2); k=1:e; r=nchoosek(n,2); B=zeros(n,n,r,r);
for i=1:r for j=1:r R([i j],:)=R([j i],:); F=R(k,:); A=zeros(n,n); for m =1:e; A(F(m,1),F(m,2))=1; A(F(m,2),F(m,1))=1;
end
B(:,:,i,j)=A;
end
end
return in this output has more duplicate matrices i want only distinct matrices. i need the code of comparing the matrices and find which is distinct
Ismet Ozturk
Ismet Ozturk 2018-3-29
编辑：Ismet Ozturk 2018-3-29
function [ a ] = deleteRepetation( a )
leng=size(a);tempa=zeros(1,2);
for i=1:leng(1)
tempa=a(i,:);
tempa=sort(tempa);
a(i,:)=tempa;
end
deletionList=[1];
while size(deletionList)>0
deletionList=[];leng=size(a);
for i=1:leng(1)
tempa=a(i,:);
for j=i+1:leng(1)
if tempa==a(j,:)
deletionList=[deletionList j];
end
end
end
a(deletionList,:)=[];
end
  1 个评论
Life is Wonderful
Life is Wonderful 2020-4-12
Couple of things noted and suggestion added for the above code
Code point-1
tempa=sort(tempa);
Replace with
tempa=sortrows(tempa);
Code point-2
if tempa==a(j,:) %might NOT always work for Tables
Replace with
if isequal(tempa,a(j,:)) % better implementation

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