Parse a String Properly from a Cell Array

I have a cell array named "Factors". It is 617 x 1. Each cell contains a string consisting of a 2 column headers and then two columns of data over 1000 rows long. I am having trouble getting the MATLAB to parse this properly.

If I open the variable in the variable editor, I can copy a single cell and paste it to Excel, and excel is capable of sorting the data properly. Two columns, 1000+ rows, exactly how i need to see it.

However, when I try to manipulate the data in MATLAB to try and pull out particular data or at least get it into a form where I can do something with it, I can't get it. I have tried to use strsplit but it is not cooperating. Does anyone have a suggestion?

Answer 1

[Star Strider]

Your ‘Factors’ cell array are strings, so getting the numeric data is not as straightforward as it might otherwise be. You can adapt this code in a loop over the various cells to retrieve and work on those you want.

D = load('Jason Allnutt Factors.mat');
F = D.Factors;
F1 = F{1};                                                  % Get First Cell (Example)
FrqAmp = F1;
Parse = regexp(FrqAmp, '\n', 'split')';                     % Split Strings By NewLine ‘\n’
NumData = cell2mat(cellfun(@str2num, Parse, 'Uni',0));      % Recover Numeric Matrix
See_Results = NumData(1:5,:)                                % Recovered Data Sample (Delete)

See_Results =

           0.01        11.16
           0.02         6.07
           0.03          3.7
           0.04         2.44
           0.05          1.7

If you want all of them in a numeric cell array, just loop through all of them and save them as numeric cells.

D = load('Jason Allnutt Factors.mat');
F = D.Factors;
for k1 = 1:size(F,1)
    Parse = regexp(F{k1}, '\n', 'split')';                     % Split Strings By NewLine ‘\n’
    NumData{k1} = cell2mat(cellfun(@str2num, Parse, 'Uni',0)); % Recover Numeric Matrix & Store In ‘NumData’
end

It takes a while to loop through them, so be patient with it. I would save the results (the ‘NumData’ cell array) as a separate .mat file so you can just load them and don’t have to parse them each time.

[Jason Allnutt]

Hey, thanks so much. This is really great. I think it'll help a lot.

Unfortunately, the 'Factors' data though has multiple different formats. Some of the data is two columns, some is 4 columns. But I think this will help for sure to get me started. Thanks again.

-Jason

[Star Strider]

My pleasure!

My code does not distinguish between 2-, 3- and 4-column cells. It converts them all correctly, because it only tests for the ‘newline’ '\n' character between lines (rows) of your cell data.

I ran it for all your cells, and it appeared to return the correct data, with either 2, 3, or 4 columns.

If my Answer solves your problem, please Accept it.

[Jason Allnutt]

Your absolutely correct. Thank you. Sorry for the mistake.

-Jason

[Star Strider]

My pleasure.

No worries — your array is so large that without parsing it, there’s no way to know the dimensions of the various cells.