A compact way to find elements of an array which are greater, equal, or less than the elements of a second array

Hi, I have two arrays a1 and a2 and I would like to get a third array b which indicates me which elements of a1 are greater, equal or less than the elements of a2. I would indicate the elements of b with 1, 0 and -1 if the elements of a1 are greater, equal or less than the elements of a2, respectively.

% input
a1 = [0 4 7 8 1 2 3]';
a2 = [4 4 6 9 9 1 1]';
% method
b = (a1>a2);
b = double(b);
b(b==0) = -1; % assign "-1" to the elements of a1 which are less than the elements of a2
c = (a1==a2);
b(find(c==1)) = 0 %  assign "0" to the elements of a1 which are equal to the elements of a2
% output
b =
    -1
     0
     1
    -1
    -1
     1
     1

Is there any, better/more compact way, maybe in a couple of lines of code to get the same result?

Answer 1

[Voss]

a1 = [0 4 7 8 1 2 3]';
a2 = [4 4 6 9 9 1 1]';

b = sign(a1-a2)

b = 7×1

-1 0 1 -1 -1 1 1

Answer 2

[Star Strider]

To check all the elements against each other —

a1 = [0 4 7 8 1 2 3]';
a2 = [4 4 6 9 9 1 1]';

Check = sign(a1 - a2.')                                         % R2016b & Later Releases

Check = 7×7

-1 -1 -1 -1 -1 -1 -1 0 0 -1 -1 -1 1 1 1 1 1 -1 -1 1 1 1 1 1 -1 -1 1 1 -1 -1 -1 -1 -1 0 0 -1 -1 -1 -1 -1 1 1 -1 -1 -1 -1 -1 1 1

Check = bsxfun(@(a1,a2)sign(a1-a2), a1, a2.')                   % All Releases

Check = 7×7

-1 -1 -1 -1 -1 -1 -1 0 0 -1 -1 -1 1 1 1 1 1 -1 -1 1 1 1 1 1 -1 -1 1 1 -1 -1 -1 -1 -1 0 0 -1 -1 -1 -1 -1 1 1 -1 -1 -1 -1 -1 1 1

.

[Sim]

@Benjamin & @Star Strider can I accept both answers?

Many thanks to both @Benjamin and @Star Strider!!!!

[Star Strider]

Only in some situations.

My pleasure!