MATLAB: Trying to store data in a matrix using loop

datenumdirloopmatrix

so I have 42 data files with names pretty much the same for example "7633_Flux_AmerifluxFormat_0(1)" and then the only thing that changes throughout the file names is the 2 numbers at the end. I would like to run a loop using dir (preferably) that sorts the files into a matrix by chronology. the file names are not in that order. The first column of all these files are dates. They have to be converted to a string and then a serial date number. I want to know how to make a loop that sorts files into a matrix by serial date number? I know this is a lot but any help or advice would be appreciate as I don't know where to begin

Best Answer

Perhaps you want this: http://blogs.mathworks.com/pick/2014/12/05/natural-order-sorting/

Related Solutions

MATLAB: Issues with sort_nat and natsortfiles; error improper matrix reference

natsortfiles returns a cell array, not a structure. Just like sort it returns the same cell array that was provided to it, just sorted into a particular order. Do you expect sort to return a structure when you pass it a cell array? As I wrote in the help quite clearly, natsortfiles has output " Y = Cell of Strings, X with all strings sorted into natural-order."

Not only did I state that the output is a cell array I also gave several examples in the FEX description, in the M-file help, and also in the HTML documentation, such as this simple example:

D = 'natsortfiles_test'; % directory path
S = dir(fullfile(D,'*.txt')); % get list of files in directory
N = natsortfiles({S.name}); % sort file names into order
for k = 1:numel(N)
  fullfile(D,N{k})
end

Notice that in all of those examples the output is a cell array (just like the input is). But you are trying to access the output as if it was a structure with fields:

cx(q).name

...but a cell array does not have fields! So once you stop trying to access the cell array as if it was a structure, and start to access the cell array using cell array indexing (just like the examples I wrote show) then that error will disappear.

MATLAB: Creating a list of strings with different numbers and same letters

This is easy using sprintf:

D = 'MyFolder';
for kk = 0:100
    fnm = fullfile(D,sprint('f%dK.csv',kk));
    MyFiles(kk+1,:) = xlsread(fnm,'E1:E2500');
end

Or using dir and my FEX submission natsortfiles to get the correct numeric order:

D = 'MyFolder'
S = dir(fullfile(D,'f*K.csv'));
N = natsortfiles({S.name});
for kk = 1:numel(N)
    fnm = fullfile(D,N{kk});
    MyFiles(kk,:) = xlsread(fnm,'E1:E2500');
end

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

https://www.mathworks.com/matlabcentral/answers/57446-faq-how-can-i-process-a-sequence-of-files

Don't forget to preallocate the output array before the loop:

https://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

Best Answer

Related Solutions

MATLAB: Issues with sort_nat and natsortfiles; error improper matrix reference

MATLAB: Creating a list of strings with different numbers and same letters

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