Cell contents assignment to a non-cell array object

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JA 2016-7-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/297357-cell-contents-assignment-to-a-non-cell-array-object

评论： Guillaume 2016-7-27

I am getting the above mentioned error while going through multiple loops. I really don't know how to explain the problem, But i will try my best

code:

function this = tempaddfilt(this,varargin)
            fc = linspace(1,200,(200/0.5));
            main = struct('seg_err',{},'sig_err',{},'filt_err',{},'fc',{});
            for a = 1:length(fc) % fc
                q = 0;
                w = 0
                for i = 1:length(this.segments) % total number signal
                    for k = 1:length(this.segments{i}) % total number of segments
                         filt_sig = eval(this.segments{i}(k).signal,this.segments{i}(k).signal(1)); % apply filter to the ith singal and kth segemnt
                        filt_sig = filt_sig';
                        main{i}(k).seg_err(a) = std(filt_sig-this.segments{i}(k).ref); % calculate the standard divitation of the filtered signal and previously calculated signal.
                        q = q+main{i}(k).seg_err(a); add all the error of the segments for the same FC
                      end
                      main{i}(1).sig_err(a) = q; % assign the sum of all error of the all segemnts of the same signal
                      w = w+main{i}(1).sig_err(a); % add all the error of the signals
                  end
                  main.filt_err = w; % assign the sum of all error of the all signals
              end
              this.error_norm = [this.error_norm ;main];
          end
      end

Basically I have 3 loops, 1st loop is for fc, 2nd loop is for signal and 3rd loop is for segemnts of the singal. Program works fine when fc = 1.

But when fc is 2, i get the following error:

Cell contents assignment to a non-cell array object.

in the line:

main{i}(k).seg_err(a) = std(filt_sig-this.segments{i}(k).ref);

that is when i =1 , k=1 ,a = 2

any help will be appriciated

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Guillaume 2016-7-27

在 MATLAB Online 中打开

Note: other than confusion between cells and structures that others have answered to, there is a very suspicious line in your code:

filt_sig = eval(something, somethingelse)

Using eval is extremely discouraged. Furthermore, eval only takes one argument and will simply ignore the second.

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Answer 1

Image Analyst 2016-7-27

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/297357-cell-contents-assignment-to-a-non-cell-array-object#answer_229921

You declared main as a struct. Structs do not use braces {}. To fix, convert braces to parentheses (). Or else declare main as a cell array with the cell function rather than the struct function.