CODEWITHSUNDEEP
matlab
Kristada673
Kristada673

Reputation: 3744

How do I extract those rows of a matrix whose elements of a column are present in an array?

Say I have a matrix, M:

9.89E+10    3.12E+10    29
8.88E+10    8.16E+10    9
9.97E+10    8.31E+10    22
8.10E+10    6.55E+10    94
2.17E+10    8.11E+09    53
6.34E+10    8.84E+10    54
5.69E+10    7.07E+10    8
9.23E+10    8.24E+10    38
8.88E+10    5.81E+10    27

And I have another array, A:

A=8.88E+10, 9.23E+10

I want all the entries in M that contain all the entries in A. That is, my output should be a matrix, N:

8.88E+10    8.16E+10    9
9.23E+10    8.24E+10    38
8.88E+10    5.81E+10    27

I can do this using a code like:

count=1;
for i=1:size(A,1)
    for j=1:size(M,1)
        if M(j,1)==A(i,1)
            extracted(count,:)=M(j,:);
            count=count+1;
        end
    end
end

But I guess there could be a one liner code in MATLAB to do this. Is there any?

Upvotes: 1

Views: 41

Answers (1)

ibezito
ibezito

Reputation: 5822

One Liner Solution

N = M(sum(ismember(M,A),2)>0,:);

Explanation

  1. The ismember function generates a binary matrix of the same size of M, which contains 1 for each value in M which exists in A and 0 otherwise.

  2. We use sum function to sum each row in that matrix. rows which sum up to a value which is bigger than 0 are rows which contains values from A.

  3. Last, we generate the out matrix by taking all the rows from M which fits to the constraint from previous stage.

Result

N =

8.88E+10    8.16E+10    9
9.23E+10    8.24E+10    38
8.88E+10    5.81E+10    27

Upvotes: 2

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