Indexing between two lists

Hello. I am fairly new to Matlab and looking for some help with the logic of indexing between two lists.

Matrix A has known distances between points.

A = 
% From      To      DistHzPub
     1       2            100
     1       3            400
     1       4           1000
     2       3            300
     2       4            900
     3       4            600

Matrix B has multiple measurements between the same points.

B = 
% From      To       DistHorz
     1       2         100.01
     1       2         100.04
     1       3         400.02
     1       3         400.05
     1       4        1000.03
     1       4        1000.01
     2       3         300.00
     2       3         300.04
     2       4         900.06
     2       4         900.02
     3       4         600.03
     3       4         600.04

My goal is to match the known distances with the measurements, like this.

C = 
% From      To      DistHzPub
     1       2            100
     1       2            100
     1       3            400
     1       3            400
     1       4           1000
     1       4           1000
     2       3            300
     2       3            300
     2       4            900
     2       4            900
     3       4            600
     3       4            600

Creating an index by hand will get me there...

     idx = [1 1 2 2 3 3 4 4 5 5 6 6]'
     C = A(idx,:)

... but I'm having a hard time figuring out how to generate the index dynamically. Matrix A and B are subject to change in values, size, and order. Thank you.

Answer 1

[Ameer Hamza]

It seems that you can just use round() on the 3rd column, but since that solution is so obvious, there might be some other reason that you want another solution.

[~, idx] = ismember(B(:,1:2), A(:,1:2), 'rows');
C = A(idx, :);

[bene1]

Perfect. Thank you!

(I simplified the values to understand the process. Rounding won't work with the real data).