Find out the rows having same values in all columns of a matrix

Hi,

I have a matrix with 4374 rows and 8 columns. I need to find the rows which have all the columns are of same values and it's repeated for 6 times.

As for example,

Let us consider a matrix, A= [ 0 0 0 0 1 0 0 ; 1 0 0 0 0 1 0; 1 0 0 0 0 1 0; 0 1 0 1 0 1 0; 1 0 0 0 0 1 0; 0 0 0 0 0 0 0; 1 0 0 0 0 1 0, 1 1 1 1 1 1 1; 1 0 0 0 0 1 0 , 0 0 1 1 0 1 0; 1 0 0 0 0 1 0; 0 0 0 0 1 0 0].

Here,0 0 0 0 1 0 0 is repeated twice and 1 0 0 0 0 1 0 is repeated for 6 times. Finally, I need to find and keep only those rows having repeated for 6 times (as like 1 0 0 0 0 1 0 in the given example) .

Can any please help me?

Answer 1

[Stephen23]

Something like this should get you started:

>> A = [0,0,0,0,1,0,0;1,0,0,0,0,1,0;1,0,0,0,0,1,0;0,1,0,1,0,1,0;1,0,0,0,0,1,0;0,0,0,0,0,0,0;1,0,0,0,0,1,0;1,1,1,1,1,1,1;1,0,0,0,0,1,0;0,0,1,1,0,1,0;1,0,0,0,0,1,0;0,0,0,0,1,0,0]
A =
   0   0   0   0   1   0   0
   1   0   0   0   0   1   0
   1   0   0   0   0   1   0
   0   1   0   1   0   1   0
   1   0   0   0   0   1   0
   0   0   0   0   0   0   0
   1   0   0   0   0   1   0
   1   1   1   1   1   1   1
   1   0   0   0   0   1   0
   0   0   1   1   0   1   0
   1   0   0   0   0   1   0
   0   0   0   0   1   0   0
>> [U,~,idx] = unique(A,'rows');
>> cnt = histc(idx,unique(idx)) % count how many times rows occur.
cnt =
   1
   2
   1
   1
   6
   1
>> out = U(cnt==6,:) % pick which the unique rows which occur >= 6 times.
out =
   1   0   0   0   0   1   0   

If you want to get those multiple row instances, then try this:

>> idr = ismember(idx,find(cnt==6));
>> A(idr,:)
ans =
   1   0   0   0   0   1   0
   1   0   0   0   0   1   0
   1   0   0   0   0   1   0
   1   0   0   0   0   1   0
   1   0   0   0   0   1   0
   1   0   0   0   0   1   0

[Sky Scrapper]

Yes, this is working. Thanks a lot!

[Sky Scrapper]

But, I need to check if and only it's repeated for 6 times not more than 6 times. then it's showing nothing (void matrix)

[Stephen23]

Change the >= into == (as shown in my edited answer).

[Sky Scrapper]

when i am running my original code, it's showing:

cnt= 54 in each rows having 81 total rows. Does it indicate that each row in my original matrix is repeated for 54 times?

[Stephen23]

"Does it indicate that each row in my original matrix is repeated for 54 times?"

The cnt values show how many times each unique row occurs in your matrix. For example, try doing this:

>> [cnt,U]
ans =
   1   0   0   0   0   0   0   0
   2   0   0   0   0   1   0   0
   1   0   0   1   1   0   1   0
   1   0   1   0   1   0   1   0
   6   1   0   0   0   0   1   0
   1   1   1   1   1   1   1   1
% cnt | unique rows

You can see for example, that row [0,0,0,0,1,0,0] occurs twice in A.

[Sky Scrapper]

okay, got the answer. I have a matrix of 4374. after counting it's showing 81 rows and 54 times repeted. that means = (54*81)= 4374.

So, you are right. Thank you very much!

[Sky Scrapper]

In my real matrix, i have,

A=[100 50 0 -100 0 0 0 0 1 0 0 80

100 70 0 0 0 1 0 0 0 0 1 88

100 -100 0 0 1 0 0 0 0 1 0 0

100 -100 100 0 0 1 0 1 0 1 0 95

100 100 0 -100 1 0 0 0 0 1 0 100

100 100 0 0 0 0 0 0 0 0 0 99

100 0 0 0 1 0 0 0 0 1 0 100

100 0 100 0 1 1 1 1 1 1 1 100

100 0 0 100 1 0 0 0 0 1 0 0

100 0 0 0 0 0 1 1 0 1 0 100

100 0 100 0 1 0 0 0 0 1 0 100

100 0 0 100 0 0 0 0 1 0 0 42]

I will have to delete rows having repeated values from column 5 to 11. For this, I am doing:

[U,~,idx] = unique(A(:,5:11),'rows');

Then it's showing only the valid rows havinng column 5 to 11 but I need the valid total rows.

Could you please help me?

[Stephen23]

Perhaps this is what you are looking for:

[~,idy,idx] = unique(A(:,5:11),'rows')
U = A(idy,:)

If not you will have to show what the expected output should be.

[Sky Scrapper]

yes, that's I want. thank you so much!