MATLAB how to automatically read a number of files - matlab

Question

I would like to plot a number of 3D graphs from different data files. For example I am using
fid = fopen('SS 1.dat','r');
to read the first file and then plot a graph. How to set the program to change the name to 'SS 2.dat' automatically? Also for the tenth file the name becomes 'SS 10.dat' which has one space less (i.e.only two space between SS and 10) then the first to ninth files. How to set the program to adjust for that? Thank you.

Answer 1

Use dir:
filenames = dir('*.dat'); %//gets all files ending on .dat in the pwd
for ii =1:length(filenames)
fopen(filenames(ii),'r');
%//Read all your things and store them here
end
The beauty of dir as opposed to the other solutions here is that you can get the contents of the pwd (present working directory) in one single line, regardless of how you called your files. This makes for easier loading of files, since you do not have any hassle with dynamic file names.

Answer 2

The following code displays a lazy way to print the names from 1 to 999 that you mentioned:
for ii=1:999
ns = numel(num2str(ii));
switch ns
case 1
fname = ['ss ' num2str(ii) '.dat'];
case 2
fname = ['ss ' num2str(ii) '.dat'];
case 3
fname = ['ss ' num2str(ii) '.dat'];
end
end
Another way:
is to use the backslash character in the formatting of the filename as follows:
fstr = 'ss ';
for ii = 1:999
ns = numel(num2str(ii));
for jj = 1:ns-1
fstr = [fstr '\b'];
end
ffstr = sprintf(fstr);
fname = [ffstr num2str(ii) '.dat'];
disp(fname);
end
there are many better ways to do this though

Answer 3

prefix = 'SS';
for n = 1:10
if n == 10
filename = [prefix ' ' num2str(n) '.dat'];
else
filename = [prefix ' ' num2str(n) '.dat'];
end
fid = fopen(filename, 'r');
...
end