Create single structure array with variables in for loop.

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Vincent Scalfani
Vincent Scalfani 2018-7-17
回答： OCDER 2018-7-17
Hello, I am processing a series of text files that I then need to save the variables in each iteration for further manipulation within Matlab. I have followed the Matlab FAQ Wiki to process the files as shown below and save variables at each iteration. What happens, however, is that I create a separate .mat structure array for each file, which I then need to index the data out of:
data1 = load('myfilename1.mat')
data1 = data1.x
data2 = load('myfilename2.mat')
data2 = data2.x
What I would like to to do is create a single .mat structure array file where each string array within the structure array is the file name. So, for example, that would make loading the processed files easy, like this:
alldata = load('alldata.mat')
data1 = alldata.myfilename1
data2 = alldata.myfilename2
data3 = alldata.myfilename3
etc.
Thanks very much, here is my current code below, which works fine but is then incredibly clunky to load the data back into Matlab. Actually, I would prefer to not even save the files and just load the variables into the workspace with the filenames, but from my understanding, that is not recommended.
% Specify the folder where the files live.
myFolder = 'H:\mypath';
% Check to make sure that folder actually exists, warn if it does not.
if ~isdir(myFolder)
errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
uiwait(warndlg(errorMessage));
return;
end
% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.txt');
theFiles = dir(filePattern);
for k = 1 : length(theFiles)
baseFileName = theFiles(k).name;
fullFileName = fullfile(myFolder, baseFileName);
fprintf(1, 'Now reading %s\n', fullFileName);
% Import data as character string
x = fileread(fullFileName);
x = cellstr(x);
% do a bunch of manipulations removed here for clarity
% convert data to string arrays
x = string(x);
% name and save as a .mat file
name = strrep(baseFileName,'.txt','.mat');
save(name,'x')
end
  1 个评论
Luke McLellan
Luke McLellan 2018-7-17
You could try creating a cell of arrays for your data and then implement something along the lines of
Cell_Matrix = zeros(x,y);
for z = 1:length(Cell)
Cell_Matrix(z,:) = Cell{1,z,:};
end

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采纳的回答

OCDER
OCDER 2018-7-17
%Creating some example files storing example x's
for k = 1:10
x = rand(3);
save(sprintf('myfilename%d.mat', k), 'x');
end
%Get the file names
AllFiles = dir(fullfile(baseDir, 'myfilename*.mat'));
AllFiles = fullfile({AllFiles.folder}, {AllFiles.name});
%Get the variable 'x' from all your file names
GetVar = 'x'; %The variable you want to get
AllX = cellfun(@(z) z.(GetVar), cellfun(@(z) load(z, GetVar), AllFiles, 'un', 0), 'un', 0); %Unwrapping twice... (maybe someone knows a cleaner way?)
AllX is a cell array storing all the values 'x' per cell in order of the file name
%Might have to re-sort file names and AllX as you'll get order like
myfilename1
myfilename10
myfilename2
myfilename3
See this for natural sorting code: https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

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