0-1 sparse representations?

[E R]

I'm interested if Octave has the ability to represent a 0-1 sparse
matrix where there is only one 1 per row.

For example, it seems that Octave has a special representation for
permutation matricies:

  a = eye(3)([3,1,2],:); whos;

The storage for a is only 12 bytes, i.e. 3 4-byte integers.

However, in this case:

  b = eye(3)([1,3,3],:); whos;

the storage for b is 72 bytes - i.e. 9 8-byte doubles.

Does Octave has a special representation for a 0-1 matrix where there
is only one 1 per row, and, if so, how does one go about building it?