i've a matrix of 6x4 and i want to count the rows how many times it occur in a matrix

Question

Raman 2013-5-8

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/75009-i-ve-a-matrix-of-6x4-and-i-want-to-count-the-rows-how-many-times-it-occur-in-a-matrix

编辑： Jan 2017-8-9

 let say the matrix is 
 A=[ 12 45 67 89
56 78 65
45 67 89
55 21 90
45 67 89
55 21 90 ]

i want the output to be as:

45 67 89 ----- 3  % because it occurs 3 times
56 78 65 ------1
55 21 90 ------2

plz help me

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Answer 1

Azzi Abdelmalek 2013-5-8

1
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https://ww2.mathworks.cn/matlabcentral/answers/75009-i-ve-a-matrix-of-6x4-and-i-want-to-count-the-rows-how-many-times-it-occur-in-a-matrix#answer_84730

在 MATLAB Online 中打开

A=[ 12 45 67 89
   34 56 78 65
   12 45 67 89
   53 55 21 90
   12 45 67 89
   53 55 21 90 ]
[a,b,c]=unique(A,'rows','stable');
v=arrayfun(@(x) sum(c==x),1:size(a,1))';
out=[a v]

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Emma Cairns 2017-8-9

I have an instance where I need to do this twice with two separate matrices and I keep getting the same output for both using this code, is there any way I can make it work? Thanks!

Jan 2017-8-9

编辑：Jan 2017-8-9

@Emma: Yes, there is a way. Of course there is. If you post the relevant part of your code (preferably as a new question and not by high-jacking this thread), we can even suggest a solution.

Andrei's method is slightly faster and (c)leaner.

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Answer 2

Andrei Bobrov 2013-5-8

3
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/75009-i-ve-a-matrix-of-6x4-and-i-want-to-count-the-rows-how-many-times-it-occur-in-a-matrix#answer_84734

在 MATLAB Online 中打开

   A=[ 12 45 67 89
       34 56 78 65
       12 45 67 89
       53 55 21 90
       12 45 67 89
       53 55 21 90 ];
[a,c,c] = unique(A,'rows');
out = [a, histc(c,1:max(c))];