How to process multiple .csv files?

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flemingtb
flemingtb on 2 Nov 2018
Answered: flemingtb on 2 Nov 2018
I have a folder of .csv files i'd like to process as a batch, meaning perform analysis on each file individually. Here is the code to open the files, that i found. I'm getting an error i don't understand.
myFolder = 'B:\Projects\Concert\OfflineWarpGauge\FF_Data\Day1';
% Check to make sure that folder actually exists. Warn user if it doesn't.
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, '*.csv'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
for k = 1 : length(theFiles)
baseFileName = theFiles(k).name;
fullFileName = fullfile(myFolder, baseFileName);
fprintf(1, 'Now reading %s\n', fullFileName);
end
Error Message:
Function 'subsindex' is not defined for values of class 'struct'.
Error in BatchProcessFiles (line 13)
for k = 1 : length(theFiles)

Accepted Answer

Stephen23
Stephen23 on 2 Nov 2018
Edited: Stephen23 on 2 Nov 2018
You have a variable named length. This means when you write this:
for k = 1 : length(theFiles)
you are telling MATLAB that you want to indexing into the variable length using theFiles (which is a structure). Structures are not able to be used as indices, so this throws an error.
Solution: rename that variable, and call this:
clear length

More Answers (3)

madhan ravi
madhan ravi on 2 Nov 2018

flemingtb
flemingtb on 2 Nov 2018
Wow that worked. Basically it's opening each file and doing the analysis that i normally was doing one at a time. The data is a matrix of (Z) height data, where all i am doing is calculating the range and creating a contour plot for each.
The batch file code is creating the contour plots but the only range i'm getting is the range of the last file. How can i get a range value for each file?
  1 Comment
Stephen23
Stephen23 on 2 Nov 2018
Edited: Stephen23 on 2 Nov 2018
@flemingtb: see the link that madhan ravi gave: this shows how to store imported file data in a cell array. Then you can access all of that imported data using cell indexing or a comma-separated list, e.g.:
C = cell(...);
for k = ...
C{k} = ...
end
M = horzcat(C{:})

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flemingtb
flemingtb on 2 Nov 2018
Got it, thanks.

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