MATLAB load 2nd column of all files into matrix

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Benjamin Cowen
Benjamin Cowen 2018-9-19
评论： Walter Roberson 2018-9-20
I have a folder with a lot of files of the form: defects_*.txt
Assuming the path to the directory containing these files is C:/Path, how can I load all the files into MATLAB, and create a matrix that contains the 2nd column of each file in the directory.
So basically, I don't care about column 1, but I want to load in the files sequentially, defects_002.txt, defects_005.txt, etc. (no constant increment), and then take the 2nd column from each of these txt files, and paste them as separate columns in a new matrix. So I will have a new matix where column 1 is the 2nd column of defects_0.002.txt, column 2 is the 2nd column of defects_0.005.txt etc. Is this possible?
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Benjamin Cowen
Benjamin Cowen 2018-9-19
@ChristopherWallace Just 2 columns of data, with 1 header row. I just care about the 2nd column of data, not the header row though

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回答（1 个）

Walter Roberson
Walter Roberson 2018-9-20
http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F
Reading only the second column can be done in a number of different ways, depending upon the format of the data. One possible way is to use csvread with the r and c parameters both set to 1 -- the r being 1 to skip 1 header row, and the c being 1 to skip 1 column.
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Benjamin Cowen
Benjamin Cowen 2018-9-20
hmmm, i get an error
Index exceeds matrix dimensions.
Error in dlmread (line 152)
result = result{1};
Error in csvread (line 48)
m=dlmread(filename, ',', r, c);
Error in defects_v2 (line 7)
thisdata = csvread( filenames{K}, 1, 1); %skip 1 row and 1 column
Walter Roberson
Walter Roberson 2018-9-20
projectdir = 'C:/Path';
dinfo = dir( fullfile(projectdir, 'defects_*.txt') );
filenames = fullfile(projectdir, {dinfo.name});
nfiles = length(filenames);
data = [];
for K = 1 : nfiles
fid = fopen(filenames{K}, 'rt');
thisdata = cell2mat( textscan(fid, '%*f%f', 'HeaderLines', 1) );
fclose(fid);
data(1:length(thisdata), K) = thisdata;
end

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