Open multiple files with fopen
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I have written two codes in matlab:
The first one is:
files=dir('*.csv');
for i=1:length(files)
fid(i)=fopen(files(i).name);
files(i).values=textscan(fid(i), '%f %f','delimiter',',','HeaderLines',20,'MultipleDelimsAsOne',1);
end
and the second one is:
str='C:\Users\user\Measurements\Test';
folder_name=uigetdir(str);
files=dir(fullfile(folder_name,'*.csv'));
for i=1:length(files)
fid(i)=fopen(files(i).name);
files(i).values=textscan(fid(i), '%f %f','delimiter',',','HeaderLines',20,'MultipleDelimsAsOne',1);
end
The first code is saved in the same folder as the files that I want to open. The second code is saved outside the folder where the files are stored. But both should read the same files. In the first code the structure files.values is composed by a 1x2 cell. Both cells contain a column vector with numerical values The problem arises in the second code which sometimes gives me an error because fid=-1 or the column vectors in the structure files.values are empty.
How can I overcome this problem?
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Answers (3)
Walter Roberson
on 26 Apr 2013
Is there a reason to keep the fid's around? Often you would fclose() right after the textscan. This can be important in preventing you from running out of files.
When you do the fopen() ask for the message output. Then test the fid and if it is -1, display the message (and the file name.)
0 Comments
Giorgos Papakonstantinou
on 26 Apr 2013
Edited: Giorgos Papakonstantinou
on 26 Apr 2013
5 Comments
Walter Roberson
on 16 Apr 2020
[fid(i),msg]=fopen(files(i).name);
should be
[fid(i),msg]=fopen( fullfile(folder_name, files(i).name));
Giorgos Papakonstantinou
on 26 Apr 2013
1 Comment
Stephen23
on 17 Apr 2020
Using cd should be avoided in code.
Using absolute/relative filenames is more efficient, robust, simple, and easier to debug, e.g.:
D = 'C:\Users\user\Measurements\Test';
S = dir(fullfile(D,'*.csv'));
for k = 1:numel(S)
F = fullfile(D,S(k).name);
[fid,msg] = fopen(F,'rt');
assert(fid>=3,msg)
S(k).values = textscan(fid,...);
fclose(fid);
end
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