Error: "Cell contents assignment to a non-cell array object."

Hello,

I am getting the error "Cell contents assignment to a non-cell array object" on a single line which is attempting to assign a variable into a previously created cellarray. The code does this many times, however, it is only getting stuck at this one and I can't figure out why. I have checked the brackets used and some other tips I found in the forum.

Thanks for the help. The code is below. The error is on line 135 (Glx_AlphaTissCorr{count} = Glx_AlphaTissCorr;)

source_path = 'B:\BBA\Gannet\Tests\Test_batchAllSteps\Test_batchWithWater_7.26.18\GannetQuantify_output'; %where we are pulling data (.mat files) from
final_path = 'B:\BBA\Gannet\Tests\Test_batchAllSteps\Test_batchWithWater_7.26.18\GannetQuantify_output'; %where to output excel file

keyword = 'MRS_struct';

%need to declare variables/arrays as zero so we can add to them in loops
cd(source_path)

%%Make empty arrays with N_max, 1 dimension to hold N data.
%1, N_max is row, N_max,1 is column
N_max = 100;
count = 0;
MAT_filename_cellarray = cell(N_max,1);

%Empty cell arrays here that we will fill later
%Data input in comment to right of empty array line below

%GABA cell arrays
GABACr_cellarray  = cell(N_max,1); %from output: ConcCr
GABAIU_cellarray = cell(N_max,1);%from output: ConcIU
GABAFitError_cellarray = cell(N_max,1);%from output: FitError
GABA_CSFCorr_cellarray = cell(N_max, 1);%from output: ConcIU_CSFCorr
GABA_TissCorr_cellarray = cell(N_max, 1);%from output: ConcIU_TissCorr
GABA_AlphaTissCorr_cellarray = cell(N_max, 1); %from output: ConcIU_AlphaTissCorr
GABA_AlphaTissCorr_GrpNorm_cellarray = cell(N_max, 1); %from output: ConcIU_AlphaTissCorr_GrpNorm

%Glx cell arrays
GlxCr_cellarray  = cell(N_max,1); %from output: ConcCr
GlxIU_cellarray = cell(N_max,1); %from output: ConcIU
GlxFitError_cellarray = cell(N_max,1); %from output: FitError
Glx_CSFCorr_cellarray = cell(N_max, 1); %from output: ConcIU_CSFCorr
Glx_TissCorr_cellarray = cell(N_max, 1); %from output: ConcIU_TissCorr
Glx_AlphaTissCorr_cellarray = cell(N_max, 1); %from output: ConcIU_AlphaTissCorr
Glx_AlphaTissCorr_GrpNorm_cellarray = cell(N_max, 1); %from output: ConcIU_AlphaTissCorr_GrpNorm

%Tissue composition cell arrays
GMFra_cellarray = cell(N_max, 1); %from output: GMfra
WMFra_cellarray = cell(N_max, 1); %from output: WMfra
CSFfra_cellarray = cell(N_max, 1); %from output: CSFfra

%output_xls_filename = 'Gannet_MAT_Output';

%%Read Data + set variables to load into arrays / export at end
display (' look for MAT files in Quantify folder');
MAT_file_location = dir([source_path, '/*.mat']);%list all conent from location of MAT files

for i = 1: length(MAT_file_location);

   %%%Suggestion from forum. Can use instead of strfind
    %   F = sprintf('*%s*.mat', keyword);
    %  S = dir(fullfile(source_path, F));
     % for k = 1:numel(S)
      %    tmp_ = load(fullfile(F,S(k).name));

      if(strfind(MAT_file_location(i).name, keyword)); %if file has MRS_struct in name

          %load mat files to array- loading file we found at top of loop with
          %keyword etc
          tmp = load(MAT_file_location(i).name); % getting the name and ext. of file "MRS_struct.mat"
                                                 % tmp is now MRS_struct file
          count = count + 1;

          display ('Look for data from MRS_struct');

          %dont put these values in '' or it will be string, this gives data

          display ('Getting GABA data from MRS_struct');
          %GABA Data from MRS_struct-- here we are getting values from MRS
          %struct and assigning to variables
          GABACr = tmp.MRS_struct.out.vox1.GABA.ConcCr(i);
          GABAIU = tmp.MRS_struct.out.vox1.GABA.ConcIU(i);
          GABAFitError = tmp.MRS_struct.out.vox1.GABA.FitError(i);
          GABA_CSFcorr = tmp.MRS_struct.out.vox1.GABA.ConcIU_CSFcorr(i);
          GABA_TissCorr = tmp.MRS_struct.out.vox1.GABA.ConcIU_TissCorr(i);
          GABA_AlphaTissCorr = tmp.MRS_struct.out.vox1.GABA.ConcIU_AlphaTissCorr(i);
          GABA_AlphaTissCorr_GrpNorm = tmp.MRS_struct.out.vox1.GABA.ConcIU_AlphaTissCorr_GrpNorm(i);

          display ('Getting Glx data from MRS_struct');
          %Glx Data from MRS_struct
          GlxCr = tmp.MRS_struct.out.vox1.Glx.ConcCr(i);
          GlxIU = tmp.MRS_struct.out.vox1.Glx.ConcIU(i);
          GlxFitError = tmp.MRS_struct.out.vox1.Glx.FitError(i);
          GlxIU_CSFcorr = tmp.MRS_struct.out.vox1.Glx.ConcIU_CSFcorr(i);
          Glx_TissCorr = tmp.MRS_struct.out.vox1.Glx.ConcIU_TissCorr(i);
          Glx_AlphaTissCorr = tmp.MRS_struct.out.vox1.Glx.ConcIU_AlphaTissCorr(i);
          Glx_AlphaTissCorr_GrpNorm = tmp.MRS_struct.out.vox1.Glx.ConcIU_AlphaTissCorr_GrpNorm(i);

          display ('Getting Tissue data from MRS_struct');
          %Tissue Concentration Data from MRS_struct
          GMFra = tmp.MRS_struct.out.vox1.tissue.GMfra(i);
          WMFra = tmp.MRS_struct.out.vox1.tissue.WMfra(i);
          CSFfra = tmp.MRS_struct.out.vox1.tissue.CSFfra(i);

          %Here we are assigning above data to empty arrays created earlier
          %We will then export them below

          display ('Assigning data to arrays');
          %Loading GABA variables/data into arrays
          MAT_filename_cellarray{count} = MAT_file_location(i).name;
          GABACr_cellarray{count}  = GABACr;
          GABAIU_cellarray{count} = GABAIU;          
          GABAFitError_cellarray{count} = GABAFitError;
          GABA_CSFCorr_cellarray{count} = GABA_CSFcorr;
          GABA_TissCorr_cellarray{count} = GABA_TissCorr;
          GABA_AlphaTissCorr_cellarray{count} = GABA_AlphaTissCorr;
          GABA_AlphaTissCorr_GrpNorm_cellarray{count} = GABA_AlphaTissCorr_GrpNorm;

          %Loading Glx variables/data into arrays
          GlxCr_cellarray{count} = GlxCr;
          GlxIU_cellarray{count} = GlxIU;
          GlxFitError_cellarray{count} = GlxFitError;
          GlxIU_cellarray {count} = GlxIU;
          GlxFitError_cellarray{count} = GlxFitError;
          Glx_CSFCorr_cellarray{count} = GlxIU_CSFcorr;
          Glx_TissCorr_cellarray{count} = Glx_TissCorr;
          Glx_AlphaTissCorr{count} = Glx_AlphaTissCorr;
          Glx_AlphaTissCorr_GrpNorm_cellarray{count} = Glx_AlphaTissCorr_GrpNorm;

          display ('tissue conc');
          %Loading Tissue Conc variables/data into arrays
          GMFra_cellarray{count} = GMFra;
          WMFra_cellarray{count} = WMFra;
          CSFfra_cellarray{count} = CSFfra;

          count = count + 1;
      end
  end

%array of headers, values-- MAKE SURE THESE ARE IN THE SAME ORDER
%put these 2 into an outputcell and write to excel

display ('Getting ready to output')
output_header_cellarray = ... %Headers for output document
[{'PID'},{'GABAConcCr'}, {'GABAConcIU'}, {'GABAFitError'}, {'GABA_CSFCorr'}, {'GABA_TissCorr'}, {'GABA_AlphaTissCorr'} , {'GABA_AlphaTissCorr_GrpNorm'} , {'GlxConcCr'} , {'GlxConcIU'} , {'GlxFitError'} , {'Glx_CSFCorr'} , {'Glx_TissCorr'} , {'Glx_AlphaTissCorr'} , {'Glx_AlphaTissCorr_GrpNorm'} ];

output_value_cellarray = ...%Data that goes into each column
[MAT_filename_cellarray,GABACr_cellarray, GABAIU_cellarray, GABAFitError_cellarray, GABA_CSFCorr_cellarray, GABA_TissCorr_cellarray, GABA_AlphaTissCorr_cellarray, GABA_AlphaTissCorr_GrpNorm_cellarray , GlxCr_cellarray , GlxIU_cellarray , GlxFitError_cellarray, Glx_CSFCorr_cellarray , Glx_TissCorr_cellarray , Glx_AlphaTissCorr_cellarray , Glx_AlphaTissCorr_GrpNorm_cellarray];

output_cell = [output_header_cellarray; output_value_cellarray]; %write header + value cellarrays

output_xls_filename = 'Gannet_Quantify_Extract';
xlswrite(output_xls_filename, output_cell);

[Image Analyst]

It would be easier for people to debug it if you attached a .mat file with the data needed to run your program.

[Adam Danz]

What is the value of this on the iteration that causes the error?

class(tmp.MRS_struct.out.vox1.Glx.ConcIU_AlphaTissCorr(i))

[Holly Pothier]

Image Analyst- I can't send the MRS_struct file because it is too big, and will not compress to a smaller size .zip.

Adam Danz- The data point values are 4.8 and 5.9. It fails on the first iteration. There is only one .mat file called MRS_struct in the folder, so it should only do one iteration. It just stops at the error and does not continue.

[Adam Danz]

I was looking for the class() not the values within the variable. Anyway, clearly it's not a cell() as the answer below explains.

[Walter Roberson]

Glx_AlphaTissCorr{count} = Glx_AlphaTissCorr

Notice that you are assigning to the same variable as you are reading from and you are asking to store the entire variable to a part of the variable. That typically only makes sense in certain linked list type procedures.

[Holly Pothier]

Adam Danz- The class is 'double'.

Answer 1

[Guillaume]

Error on

Glx_AlphaTissCorr{count} = Glx_AlphaTissCorr

Well, the error is clear, Glx_AlphaTissCorr is not a cell array.

Even if it were, the line makes no sense as it tries to assign a variable as a member of itself. Considering that all your cell arrays are named xxx_cellarray, the left hand side is suspicious. And considering that on the previous line, you've already assigned Glx_AlphaTissCorr to its corresponding cell array, I suspect that the fix is to simply remove the offending line.

[Holly Pothier]

Thank you for pointing that out. I don't know why I didn't notice that simple mistake.