Expression for summing all the entries of a logical matrices expressions in Matlab?

Question

To sum all the elements in a matrix you usually do

A = sum ( B(:) );

which is nice and short. However assume that we have a logical expression like this

B = B == 6

and we want to sum the elements of all the entries, then smartest way seems to be to do

A = sum ( sum ( B == 6 ) )

or

B = B == 6;
A = sum( B(:) );

Both are kind of ugly. So I was wondering is there a nicer expression?

A = sum ( (B == 6)(:) );

Would be nice but doesn't work.

A = sum ( (B == 6)(:) ); doesn't work? – varunl Oct 03 '11 at 01:58 — varunl, Oct 03 '11 at 01:58

score 3 · Accepted Answer · answered Oct 03 '11 at 01:54

3

So what is so nasty about the simple solution...

A = sum(B(:) == 6);

answered Oct 03 '11 at 01:54

score 0 · Answer 2 · edited May 23 '17 at 12:12

0

Not that I recommend this, but as was shown previously, you can actually do something like:

%# A = sum ( (B == 6)(:) )
A = sum( subsref(B == 6, struct('type','()', 'subs',{{':'}})) )

edited May 23 '17 at 12:12

Community

answered Oct 04 '11 at 00:41

Amro

2 Answers2