Is there a way in MATLAB to make a boundary and have it skip over data pairs?

I am attempting to make a boundary out of data that is somewhat incomplete. I have been replacing the NaN with 0's, but then the boundary shows up on my graph covering an area I suspect is not accurate. Is there a loop that would allow MATLAB to read the data and make a boundary only out of pairs of data that do not include NaN?

For example, if the data sets are:

m = [0 NaN 2 3 5 NaN]
a = [NaN 2 3 4 5]

I would want to make it so that if I were to make a boundary

am_boundary = boundary(a, m);

then I could use an if loop or something else to only make the boundary out of the third, fourth and fifth data pairs.

Thanks!

Answer 1

[per isakson]

Documentation of the function, boundary(x,y), says

• x and y shall be column vectors
• x and y shall be of equal length

Try

%%equal length
m = [0 NaN 2 3 5 NaN];
a = [NaN 2 3 4 5, nan ];
%%column vectors
m = reshape( m, [], 1 );
a = reshape( a, [], 1 );
ixnonan = find( not(isnan(m)|isnan(a)) );
k = boundary( a(ixnonan), m(ixnonan) ); 
k = [ ixnonan(k(1:end-1)); ixnonan(k(1)) ];
am_boundary = [ a(k), m(k) ];
plot( m, a, 'd' )
hold on
plot( m(k), a(k) )

[Hannah Bercovici]

Thank you so much! This worked like a charm.