Compare two matrices of different dimensions

I have a matrix B of dimension bx2 and a matrix A of dimension ax5 with the following characteristics:

B=[3  1;
   3  2;
   3  3;
   5 18] %In the first column of B elements are always in ascending order but can be repeated more than once

A=[1 18 19 19 20;
   2  7  8  9 10;
   3  1  2  2  3;
   4 18 19 19 20;
   5 18 19 19 20;
   6 11 12 13 14] %In the first column of A elements are always in ascending order, they start from 1 and end at a=6 and they are at a distance of 1

I want to construct a matrix C of dimension ax5

 C=[1 0 0 0 0;
    2 0 0 0 0;
    3 1 1 1 1;
    4 0 0 0 0;
    5 1 0 0 0;
    6 0 0 0 0]

In C I do the following: I take A(i,1) and pick the rows j of A with B(j,1) equal to A(i,1); for these rows I pick B(j,2) and reports C(i,h)=1 is B(j,2)=A(i,h).

If B(:,1) started with 1 and ended with 6 a possible answer would be

   x = accumarray(B(:,1),B(:,2),[max(B(:,1)),1],@(x){x});
   C = [A(:,1),cell2mat(arrayfun(@(z)ismember(A(z,2:end),x{z}),A(:,1),'un',0))]

as suggested here

http://www.mathworks.co.uk/matlabcentral/answers/127614-how-to-compare-two-matrices-of-different-dimensions

But in this case B(:,1) does not necessarily start with 1 and end with 6 even if it has for sure elements <=6 and >=1

[Geoff Hayes]

Cris - Could you post your initial go of the MATLAB code to solve this problem (since you have the C "pseudo-code")?

[the cyclist]

Should the third row of C actually be

[3 1 1 1 1]

?

[MRC]

Yes, thanks question edited.

Answer 1

[the cyclist]

B=[3  1;
   3  2;
   3  3;
   5 18] %In the first column of B elements are always in ascending order but can be repeated more than once

A=[1 18 19 19 20;
   2  7  8  9 10;
   3  1  2  2  3;
   4 18 19 19 20;
   5 18 19 19 20;
   6 11 12 13 14] %In the first column of A elements are always in ascending order, they start from 1 and end at a=6 and they are at a distance of 1

C = zeros(size(A));
C(:,1) = A(:,1);

for ii = 1:size(A,1)
    C(ii,2:end) = ismember(A(ii,2:end),B(B(:,1)==ii,2:end))
end

[MRC]

Any idea without looping?