logical indexing for row-wise average

How can I get a row-wise mean of this matrix

      1 2 3
  A = 4 5 6
      7 8 9

but I only want to select these entries

      0 1 1
  B = 1 1 0
      1 0 1

so the result would be something like

      2.5
  C = 4.5
      8.0

Actually, this is easily possible with a loop, but I'd prefer a 1-line code. (this one is just a question of beauty :-))

Answer 1

[Matt J]

 C=sum(A.*B,2)./sum(B,2);

[Vincent]

thanks, quite clever using .* instead of indexing, thank you! :-)