extract a row of 2D array based on constant 2D array values

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hi I am trying to pull out / extract number of rows from a 2D array data based off from another 2D array (1 row).
For example,
A = [90 10 21; 90 20 21; 90 30 21; 90 40 22; 90 50 21; 88 10 20; 88 20 20; 88 30 24;
88 40 22; 88 50 21; 86 10 20; 86 20 21; 86 30 20; 86 40 25; 86 50 20]
A = 15×3
90 10 21 90 20 21 90 30 21 90 40 22 90 50 21 88 10 20 88 20 20 88 30 24 88 40 22 88 50 21
B = [14 26 30 47]
B = 1×4
14 26 30 47
result = [90 10 21; 90 30 21; 90 30 21; 90 50 21; 88 10 20; 88 30 24;
88 30 24; 88 50 21; 86 10 20; 86 30 20; 86 30 20; 86 50 20]
result = 12×3
90 10 21 90 30 21 90 30 21 90 50 21 88 10 20 88 30 24 88 30 24 88 50 21 86 10 20 86 30 20
I want to pull the entire row of A if the 2nd column of A has the closest value from B. But the second column of A is repeating 10 - 50.
I tried the interp1 (A,A,B,'nearest') but it does not work since B must be a target value.
Can you suggest any other solutions?
  4 Comments
Dyuman Joshi
Dyuman Joshi on 3 Oct 2023
The criteria/logic to get the output result from the inputs A and B is still not clear to me.
Could you elaborate on it?
Min
Min on 3 Oct 2023
Sure!
Well a quick update is that it does not need to be nearest anymore. I just found a way to get those values.
I was wondering if there is a way to extract a number of rows based on the 'B' array values.
So
let's say
A Column name: Column 1 = Distance, Column 2 = Angle, Column 3 = something else
where A = [90, 10, 21; 90, 20, 21; 90, 30, 21; 90, 40, 22; 90, 50, 21; 88, 10, 20; 88, 20, 20; 88, 30, 24; 88, 40, 22; 88, 50, 21; 86, 10, 20; 86, 20, 21; 86, 30, 20; 86, 40, 25; 86, 50, 20]
Then based on the Array 'B' where B = [14; 26; 30; 47]
Then it will select and extract the a number of rows from A when column 2 of A has the nearest B values.
Essentially, extracting the rows when it matches another array.

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Accepted Answer

Voss
Voss on 3 Oct 2023
Edited: Voss on 3 Oct 2023
A = [90 10 21; 90 20 21; 90 30 21; 90 40 22; 90 50 21; 88 10 20; 88 20 20; 88 30 24; 88 40 22; 88 50 21; 86 10 20; 86 20 21; 86 30 20; 86 40 25; 86 50 20]
A = 15×3
90 10 21 90 20 21 90 30 21 90 40 22 90 50 21 88 10 20 88 20 20 88 30 24 88 40 22 88 50 21
B = [14; 26; 30; 47]
B = 4×1
14 26 30 47
[~,~,jj] = unique(A(:,1),'stable');
result = splitapply(@(x)get_rows_near(x,B(:).'),A,jj);
result = vertcat(result{:});
disp(result);
90 10 21 90 30 21 90 30 21 90 50 21 88 10 20 88 30 24 88 30 24 88 50 21 86 10 20 86 30 20 86 30 20 86 50 20
function out = get_rows_near(x,B)
[~,idx] = min(abs(x(:,2)-B),[],1);
out = {x(idx,:)};
end
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