two arrays mapping value

Hi, I have two arrays A=[1 0.1452; 2.1 0.2487; 3.2 0.3478; 4.8 0.41123] and B=[0.4 0.5 2.5 3.5 1.7]. I wanna get the mapping value of B from A. The rule is to find the ceil value of B in first column of A and return value in second column of A.For example, the ceil value of 1.7 in first column of A is 2.1, so the mapping value is 0.2487. Finally, the mapping value of B is [0.1452 0.1452 0.3478 0.41123 0.2487]. The size of B is over 10000. Please tell me the faster and more efficient method to solve it. Thanks

Answer 1

[Vishal Rane]

A((A(:,1) == min(A(A(:,1) > B(1)))),2)

[Vishal Rane]

run this in a for loop by indexing B(i) or use this

arrayfun( @(x)( A((A(:,1) == min(A(A(:,1) > x))),2)), B)

Answer 2

[Jan]

B(B > max(A(:, 1)) = NaN;  % B too large
[dummy, index] = histc(B, [-Inf, A(:, 1).']);
outOfRange     = (index == 0)
Result         = A(index(~outOfRange), 2);

I cannot test this currently. Please care about the exceptions like values of B, which are greater or equal the maximum value of A. The CEIL criterion is not fulfilled, when an element of B is exactly contained in A. But HISTC is the general way to go through.