Merge matrices

(in a SQL equijoin)

Description

Function JOINMAT implements SQL 'join' operation with a single equality condition.

http://en.wikipedia.org/wiki/Join_(SQL)

It has been tested with numeric keys only, and not optimized; improvements are enthusiastically welcomed.

See also the dataset-array version JOINDST.

PS. Note that output rows are sorted, and Inf values are treated in the same way as (but are distinguished from) NaN values.

• MATLAB release: MATLAB 7.4 (R2007a)

[Phil from AL]

Just what I was looking for. Wonder why MW released a 'join' (kinda) for datasets but not for matrices.

[Jesse Blocher]

Brilliant - this saved me a ton of time from either setting up mySQL or otherwise exporting out of Matlab elsewhere to do the join. Again, brilliant.

[David Divad]

Unfortunately this does not seem to work always well.

Consider:

A = [1 1; 1 2; 1 3; 1 4]
C = [1 8; 1 9]
joinmat(A,C,'inner') % does not give cartesian product -> joinmat only works with unique keys in at least one of the matrices

ans =

     1 1 8
     1 2 9
     1 3 8
     1 4 9
     1 1 8
     1 2 9
     1 3 8
     1 4 9

Does anybody know a good alternative to this? How can I join two matrices in MATLAB (without unique keys)?