Make spceficic array values zero.

Hi Mathworks community!

I'm having trouble trying to make some of my array values zero. This array corresponds to my Input:

Input = [-1 0 -1 0 0 NaN NaN NaN NaN  -1 0 -1 -1 -1 0 NaN NaN NaN 0 0 -1 0 -1 NaN NaN NaN]

I'd like to make everything inside the array zero, but the last -1 before every NaN series. This should be the expected Output:

Output = [0 0 -1 0 0 0 0 0 0  0 0 0 0 -1 0 0 0 0  0 0 0 0 -1 0 0 0]

Could someone please help me out?

Thank you,

Santos

Answer 1

[David Hill]

a=find(diff(isnan(Input))==1);
b=find(Input==-1);
Output=zeros(size(Input));
for k=a
    Output(b(find(b<=k,1,'last')))=-1;
end

[Santos García Rosado]

Thank's for the help David. Do you know some other way of doing it avoiding 'last'? I'll be using this code in Simulink and I know this kind of functions aren't supported. Nevertheless, thank's for your answer!

[David Hill]

You could do something like:

Input = [-1 0 -1 0 0 NaN NaN NaN NaN  -1 0 -1 -1 -1 0 NaN NaN NaN 0 0 -1 0 -1 NaN NaN NaN];
Output=zeros(size(Input));
idx=[];
for k=1:length(Input)
    if Input(k)==-1
        Output(k)=-1;
        idx=[idx,k];
    end
    if isnan(Input(k))
        Output(idx(1:end-1))=0;
        idx=[];
    end
end

[Santos García Rosado]

Thank's for the quick feed back and help!