Non-singleton dimensions of the two input arrays must match each other.

a = {rand(6000,7); rand(3600,7); rand(600,7)};
mx = {randi(50,600,1), randi(50,600,1); randi(50,360,1), randi(50,360,1); randi(50,60,1), randi(50,60,1)};
mn = {randi(50,600,1), randi(50,600,1); randi(50,360,1), randi(50,360,1); randi(50,60,1), randi(50,60,1)};
q = mx;
for x = 1:size(q,1)
    for y = size(mn,2)
        b = reshape(a{x}(:,7),10,[]).';
        b = bsxfun(@minus,b,mn{x,y});
        b = bsxfun(@rdivide,b,mx{x,y}-mn{x,y});
        q{x,y} = reshape(b.',[],1);
    end
end

I want to change the following line b = reshape(a{x}(:,7),10,[]).' into b = transpose(reshape(a{x}(:,7),60,[]).') but I get an error even though both reshaping commands give me a 60 x 10 double.

Error using bsxfun Non-singleton dimensions of the two input arrays must match each other.

Where is my mistake?

Answer 1

[Stephen23]

You wish to perform an array transpose on the following line:

b = reshape(a{x}(:,7),10,[]).';

However this line already has a transpose operation .' at the end. So transposing it twice is simply equivalent to not transposing it:

b = reshape(a{x}(:,7),10,[]);

In any case, the error is telling you that the two input matrices provided to the function bsxfun must match in size on all dimensions that are not singleton. Have a look at the dimensions of the arrays used as inputs to bsxfun. Do these fit the requirements of the documentation?

You should learn to use some debugging tools , then you could figure out for yourself where this error is occurring.

[AA]

thanks for your advice. Yes they should match because logically b = reshape(a{x}(:,7),60,[]) = b = reshape(a{x}(:,7),10,[]).';

both give me a 60 x 10 double.

[Stephen23]

Actually they don't match:

>> a = {rand(6000,7); rand(3600,7); rand(600,7)};
>> x = 1;
>> b1 = reshape(a{x}(:,7),10,[]).'; % original
>> b2 = transpose(reshape(a{x}(:,7),60,[]).'); % proposed
>> b3 = reshape(a{x}(:,7),60,[]); % proposed without 2x transpose
>> size(b1), size(b2), size(b3)
ans =
   600    10
ans =
    60   100
ans =
    60   100

We can see that the original array b1 is clearly a different size from the arrays that you are trying to use now ( b2 and b3 ), regardless of what "they should be".

The error in bsxfun clearly states that the array dimensions must match each other, so the sizes of these arrays is first thing to check, as I explained to you in my answer. When programming, it really does help to consider what the code is actually doing, and not just what it should be doing.

[AA]

q = mn;
  for x = 1:size(q,1)
      for y =  1:size(mn,2)
          b = reshape(a{x}(:,7),[],10);
          b = bsxfun(@minus,b,mn{x,y});
        b = bsxfun(@rdivide,b,mx{x,y}-mn{x,y});

            q{x,y} = reshape(b,[],1);
        end
    end

[AA]

thanks for giving me the hint. the above code is what i wanted. i just removed the .'

[Stephen23]

Glad to be of assistance. This wasn't hard to track down, because the error message is pretty explicit: perhaps revising debugging in MATLAB would be worth your while.