find number of columns on text file

11 vues (au cours des 30 derniers jours)
Richard
Richard le 20 Nov 2012
Is it possible to determine the number of columns in a text file prior to importing the data into matlab?
I can determine the number of rows as follows:
fid = fopen('myFile.txt','rt');
nLines = 0;
while (fgets(fid) ~= -1),
nLines = nLines+1;
end
fclose(fid);
However, is there a way of returning the number of columns? Some of the text files that I need to import contain several column and others contain only one column therefore I require the number of columns in a specific text file in order to use textscan. Note I cannot use importdata or dlmread as some of the files contain nans.
Amended: Consider I create two text files:
d1 = 1+(30-1).*rand(365,3);
d2 = 1+(30-1).*rand(365,1);
mkdir('C:\Matlab_Q');
filename = 'C:\Matlab_Q\ex1.txt';
fid = fopen(filename,'wt');
fprintf(fid,'%f\n',d2);
fclose(fid);
filename = 'C:\Matlab_Q\ex2.txt';
fid = fopen(filename,'wt');
fprintf(fid,'%f\t%f\t%f\n',d1');
fclose(fid);
I now wish to read the number of columns in each text file:
FNames = {'ex1','ex2'};
delimiter = '\t';
for i = 1:length(FNames);
fid = fopen(fullfile('C:\Matlab_Q',[FNames{i} '.txt']),'rt');
tLines = fgets(fid);
numCols{i} = numel(strfind(tLines,delimiter)) + 1;
fclose(fid);
end
This solution returns 1 where it should return 1 and 3. How can this be solved?

Réponse acceptée

José-Luis
José-Luis le 20 Nov 2012
Modifié(e) : José-Luis le 20 Nov 2012
delimiter = ' '; %or whatever
fid = fopen('myFile.txt','rt');
tLines = fgets(fid);
numCols = numel(strfind(tLines,delimiter)) + 1;
fclose(fid);
  3 commentaires
José-Luis
José-Luis le 20 Nov 2012
Modifié(e) : José-Luis le 20 Nov 2012
You are looking for the string '\t', not for a tab. Use instead:
delimiter = char(9); %for a tab
Or
delimiter = sprintf('\t','');
Mitchell Thayer
Mitchell Thayer le 7 Jan 2013
Snagged that piece of code for use in a parsing function. Thanks!
-:- Mitchell

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