Processing data from multiple files

Hello

i have written a code for a standalone app in the app desginer that supposed to read number of excel files and process the data from them

this part of the code is responsible to read the data and assign it to variables.

[app.filenamelsr,pathname] = uigetfile({'*.xls';'*.xlsx'},MultiSelect="on");
            app.C=iscell(app.filenamelsr(1,2));
            if app.C==1
                app.Lengthlsr=length(app.filenamelsr);
            else
                app.Lengthlsr=1;
            end
             for i=1:length(app.filenamelsr)
                  LSR(i)=xlsread(fullfile(pathname,app.filenamelsr{1,i}));
                  app.t_lsr(i)=LSR(i,:,1);
                  app.S(i)=LSR(i,:,2);
                  app.r(i)=LSR(i,:,3);
                  app.dt(i)=LSR(i,:,4);
                  app.t_k(i)=app.t_lsr(i)+273;
                  app.R_r(i)=app.r(i).*(10^(5));
              end

but when i try to run it i get this error

app.filenamelsr are cells containing the file names. for example

my logic is that in order to use the first name the indices should be {1,1} and for the second {1,2} so forth. therefore for the loop it should be like that {1,i}

what did i do wrong? assume at least 2 files are loaded

thanks for the help

Answer 1

[Stephen23]

"what did i do wrong?"

You tried to assign an array into a scalar location. Some of the other indexing will not work either, for the same reason. You could avoid this by using lots of comtainer arrays or to preallocate arrays of the correct sizes and then use (non-scalar) indexing. That would work... if you like doing things in a complex way.

A simpler approach is to just store the entire matrix for each file in one cell array, then concatenate them after the loop:

[C,P] = uigetfile({'*.xls';'*.xlsx'},MultiSelect="on");
C = cellstr(C); % simpler way of handling one file
D = cell(size(C));
for k = 1:numel(C)
    F = fullfile(P,C{k});
    D{k} = readmatrix(F);
end
LSR = cat(3,D{k})
... do whatever with that array

[Dolev]

thank you very much, this will work for multiple files?

[Stephen23]

"thank you very much, this will work for multiple files?"

Of course, that is exactly what the loop is for. See also:

https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

Answer 2

[Ergin Sezgin]

Hi Dolev,

Try using curly brackets "{}" instead of parentheses. Alternatively, take a look at datastore which is another option for importing and managing data collections.