Replace Nan by a number in a cell array

Hey MATLAB guys,

I would like to replace all Nan in the following cell array r by a number. Could anyone please tell me how I can do that for the following problem? Thanks in advance

r = cell(sum(nL), numel(nL), numel(nW), max(nW(:)));
for k = 1 : numel(nW)
    for m = 1 : nW(k)
        for j = 1 : numel(nL)
            for i = 1 : nL(j)
                r{i + Nup*(j - 1), j, k, m} = .....
            end
        end
    end
end

[Rik]

This time I edited your question for you. Next time, please use the tools explained on this page to make your question more readable.

[Susan]

Sorry, I didn't know that.

Sure thing!

Answer 1

[Guillaume]

Your question is not very unclear. You show a loop filling (part) of a cell array with ... something unspecified. Presumably, that something is a matrix or vector of varying size and not a scalar (otherwise you wouldn't be using a cell array) and maybe part (all?) of it can be NaN.

If you don't want NaNs in the something, simply replace them before copying the something in the cell array:

for ...
    for ...
        something = ...
        something(isnan(something)) = somevalue;  %replace NaNs by somevalue
        r{..} = something;       
    end
end

[Susan]

Thanks Guillaume for your reply. What you mentioned is exactly what I am doing and your answer is what I was looking for. Thanks again!

Answer 2

[Rik]

You can use the isnan function:

r = cell(sum(nL), numel(nL), numel(nW), max(nW(:)));
for k = 1 : numel(nW)
    for m = 1 : nW(k)
        for j = 1 : numel(nL)
            for i = 1 : nL(j)
                if isnan(r{i + Nup*(j - 1), j, k, m})
                    r{i + Nup*(j - 1), j, k, m} = .....
                end
            end
        end
    end
end

[Susan]

Thank you so much for your reply.

[Susan]

Just a quick question,

this code just avoide the Nan, rigth? How does it replace the Nan with some other values?

Shouldn't it be something like

if isnan(r{i + Nup*(j - 1), j, k, m})
    r{i + Nup*(j - 1), j, k, m} = 'a value'
else
    r{i + Nup*(j - 1), j, k, m} = ....
end

[Rik]

That seems like it should work, yes. I just wrote the code like that because you didn't mention any context of your question, so it was/is a bit difficult to give sensible advice. You can also have a look at Guillaume's suggestion, maybe that suggestion works better for your situation.

[Susan]

Thank you so much for your reply. It helps a lot.

Answer 3

[Susan]

Hey guys! cI got another question regarding cell arrays. Any help would be greatly appreciated.

I want to implement fmincon() for this problem:

I am minimizing an objective function with respect to some variables. the variable has the following format

X =  cell(max(I(:)), numel(I), numel(I), numel(M), max(M(:)))) 

and inside each cell I have a Nt*Nr matrix. The goal is to find the optimal values of each matrix.

I defined the symbolic array of X (I am not sure if I am doing it correctly, though) and pass it to my objective function to calculate the objective function as follows:

X = cell2sym(cell(max(I(:)), numel(I), numel(I), numel(M), max(M(:))));

objfun = f(X)

but, I get the following error:

Brace indexing is not supported for variables of this type.

while I am able to get the value of f(X0) without any issue. Could anyone please kindly explain what the problem is?

Thanks in advance

[Guillaume]

You would be better off starting a new question. It's certainly not something I can help with as I don't have and know nothing about the symbolic toolbox.

[Susan]

Thanks for your reply. Sure I will.