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Easy: importing a batch of data into MATLAB 
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#1
Jul2409, 08:04 PM

P: 3

I've been going crazy trying to figure this out I'm not seeing it in the documentation. I have a few hundred files named "data*" where * goes from 000 to 300. The file type is really just a text file without any real type they aren't .txt. Is there a way to 'batch' import all of them without selecting each one individually and importing? They are all in one folder, and they are all formatted identically as having two columns.
I've been trying all sorts of tricks using data* and the 'importdata' syntax, but I'm stuck. Maybe there is a loop I can try, if you know of any. Any suggestions? 


#2
Jul2409, 09:12 PM

P: 813




#3
Jul2509, 02:23 AM

Sci Advisor
P: 1,724

If you're just starting out, MATLAB's (internal) documentation is pretty good, and the online documentation is even better (and gives quite helpful suggestions for related functionsthink Amazon without trying to sell you something). For instance, typing the following brings up the internal help for the dlmread function, delimited read from ASCII text file: >>help dlmread The online documentation for the dlmread function would be at: http://www.mathworks.com/access/help...f/dlmread.html Okay, basics aside, you can harness the interpretive nature of MATLAB using the eval function, which evaluates a text string (which you can generate on the fly!) Okay, let's assume that you want to import myData000.txt to myData999.txt (numerical data stored without a header row, and in 2 columnsseparated by commaswith 100 rowsseparated by carriage return). The following code would probably work, and produce a cell array (myData) with 1000 entries, each containing a 2x100 matrix of values.
Good luck, and remember the MATLAB inprogram and online documentation! EDIT: Forgot that when you need to put an apostrophe inside a text string, you need two of them together: '' (and no, not shiftapostrophe). Three of them together is interpreted as: put an apostrophe into the string, then terminate the string. 


#4
Jul2509, 04:54 AM

P: 1,165

Easy: importing a batch of data into MATLAB
Yes, I certainly ran into this problem when learning MATLAB. Unfortunatly I've always found MATLAB really bad for this. It has been pointed out how MATLAB allows you to do this (by writing a script). However, I've always found it more convenient to write a shell script or a c++ program to parse the data into a new MATLAB friendly file rather then deal with how MATLAB scripts these things. 


#5
Jul2509, 11:24 AM

P: 3

I'm not sure how I would go about writing a script in C++...
Thanks, MATLABdude, I'll try to get the dlmread function to work for my particular scenario and report back. 


#6
Jul2609, 01:17 PM

P: 3

I figured out a way to do this. It's very inelegant, but it definitely suffices:
for i=1:50 (just 50, say) if i<10 x=['data00',num2str(i)]; else x=['data0',num2str(i)]; end %if data(:,2*i1:2*i) = importdata(x); !this stores all the data in a matrix, 2 columns of data at a time end %for Again, nothing fancy, but it works. If I want all the first columns on the left side of the 'data' matrix and all the second columns on the right (instead of alternating first, second, first, second..) I suppose I can write to the data matrix like this: data(:,i:50:50+i) But I haven't tried that yet. Thanks for the ideas, everyone! 


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