find how many times duplicates occur in a matrix across row

Given a matrix of 2xn dimension,in the row dimension there are several numbers with duplicates.Usnig histcnt these value shave their count atmost 2.

Now I would like to ensure that I only consider those elements in the row if their count is 1,for any number i will skip them.

I tried doing unique(A(1,:)) on my matrix but it didn't give me the correct result

My current code for duplicate findinng results in index exceed error

function ids=find_indices(A,B)
ids=[];
for i=1:size(A,2)
    
    for j=1:size(B,2)
        if(A(1,i-1)==A(1,i))
            ctr=ctr+1;
        end
        %ctr=sum(A(1,:)==A(1,i));
        if (B(1,j)==A(1,i) && ctr==1)
            ids=[ids,i];
        else
            continue
        end
    end
end
end

[KSSV]

You can use unique, what problem you have with that? Show us an example and expected output.

[sparsh garg]

I have enclosed the output as well as input file.

The way i generated the output was to look at the input matrix A in that i saw that the even indices values correspond to the expected output in the range of 1:82 and the odd are to be ignored.

However this is not generalizable method

Furthermore on doing unique(A(1,:)) i got this

86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107

Columns 23 through 44

108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129

Columns 45 through 66

130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151

Columns 67 through 80

152 153 154 155 156 157 158 159 160 161 162 163 164 165

A doesn't have the values 86 and 87 yet these values are present

[Jan]

@sparsh garg: Of course the vector A(1, :) contains the values 86 and 87:

data = load('A.mat');
A    = data.A;
find(A(1, :) == 86)   % 217 220
find(A(1, :) == 87)   % 218 219

What does this mean: "Usnig histcnt these value shave their count atmost 2"?

And: "consider those elements in the row if their count is 1,for any number i will skip them"?

I do not understand, what you exactly need. Maybe you mean:

Result = unique(A.', 'rows').'

or:

[uA, idx] = unique(A(1, :));
result = [uA; A(2, idx)]

[sparsh garg]

oh sorry about that,what I wanted to say was that each value in the A matrix has a count of atmost 2 which is supported by the code snippet that you posted.

Now ,based on this I only want to select the values in A which are occuring only once. However after doing unique I am only interested in knowing the indice corresponding to these values

87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107

Columns 23 through 44

108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128.

For better visualization of what B matrix looks like ,enclosed is a plot.

Note that the figure was obtained after applying curve fitting.

[sparsh garg]

Hey Jan if possible could you give me some tips on how to go about this also

https://in.mathworks.com/matlabcentral/answers/1457689-how-to-write-design-a-matrix-similar-to-the-one-outputted-by-contourf?s_tid=prof_contriblnk

Answer 1

[Jan]

As fas as I understand, you want to obtain the indices of the elements of A, which occur once only. Then:

index  = ~isMultiple(A(1, :));
result = A(1, index);   % Or maybe sorted:

 sort(A(1, index)

function T = isMultiple(A)
[S, idx] = sort(A(:).');
m        = [false, diff(S) == 0];
ini      = strfind(m, [false, true]);
m(ini)   = true;        % Mark 1st occurence in addition
T(idx)   = m;
end