Index of Array's column whose value is closest to Vector value for a given row

Ia ora na,

I spent some time here but didn't get the hint I was looking for (yet). So, let's explain my problem. I have 2 sets : 1 vector and 1 array, same number of rows, as for example :

N = 20;
A = 1 + 4*rand(N,1); % Generate column vector of N value from 1 to 5
B = [1:0.1:5]; % Generate line vector of 41 value ranging from 1 to 5 by 0.1 step
B = repmat(B,N,1); % Replicate such vector N times

I need to get a vector idx of size [N 1] that for each rows of A(i) and B(i,:) gives me the column number of B which contains the closest value of A(i), id est : if A(1) = 3 then idx(1) should return 21 because B(1,21) = 3 is the closest value to A(1).

With or without loops, I've no idea how to get there. I already tried with find function with a loop, also the " min(abs(A-B) " thing I've seen here and there, but couldn't figure out how to get the result I need.

Thanks for your help.

Answer 1

[Chunru]

N = 20;
A = 1 + 4*rand(N,1); % Generate column vector of N value from 1 to 5
B = [1:0.1:5]; % Generate line vector of 41 value ranging from 1 to 5 by 0.1 step
B = repmat(B,N,1); % Replicate such vector N times

idx = zeros(N,1);
for i=1:N
    [~, idx(i)] = min(abs(A(i) - B(i, :)));
end

idx'

ans = 1×20

22 23 17 21 17 2 20 16 38 33 17 39 23 15 16 2 40 19 10 22

[Paul MAUGER]

Thanks for the help