Error using == Matrix dimensions must agree.

Im trying to remove bad epochs from a dataset.

I've previously substituted every bad epoch with [] inside a cell array, looking like this:

The cell array is called combine1 and is a 400x1 cell array.

i use the following code to try and remove the empty cell array elements for good

for i = 1:length(combined1)
     if combined1{i} ==[]
        combined1(i)=[]
     else
     end
 end

however i get the error:

"Error using ==

Matrix dimensions must agree."

Sadly i cant change the previous preprocessing of the data into the cell array, so i need a way to change this array.

Anyone who can spot the mistake?

Answer 1

[Stephen23]

You don't need a loop, try this:

idx = cellfun(@isempty,combined1);
combined1(idx) = []

"Anyone who can spot the mistake?"

You should have used isempty instead of comparing two matrices with incompatible sizes. Array size compatibility is explained here:

https://www.mathworks.com/help/matlab/matlab_prog/compatible-array-sizes-for-basic-operations.html

In short, arrays are compatible if for every dimension one of these is true:

• one of the arrays is scalar size for that dimension
• both of the arrays have the same size for that dimension.

Consider the two arrays that you are comparing: one has size 62x769, the other has size 0x0. Are they compatible? (hint: no)

You would also run into problems because you are trying to remove array elements from the array that you are iterating over. There are two common ways to avoid this:

1. create a logical mask and remove the elements after the loop,
2. loop over the elements backwards.

[Tim Johansson]

Thanks that solved it

And the explanation was very helpful as well.