I want to write output of code periodically in different files in some specific folder.
Code I am using is as follows:
for i=1:m
% some other things
if (mod(i,1000)==0)
y=[1:dx:n_x;c_initial.'];
fn = ['/home/alekhine' num2str(i) '.dat'];
fid=fopen(fn);
fprintf(fid,'%6.4f %12.8f\n',y);
fclose(fid);
end
end
But I am getting error from Matlab as follows
Error using ==> fprintf
Invalid file identifier. Use fopen to generate a valid file
identifier.
. What is wrong in the code? Any help will be appreciated.
You didn't give the permission argument to the fopen function, so it is opened for reading only.
See the docs (http://www.mathworks.com/help/techdoc/ref/fopen.html) for valid values for permission.
Just FYI, the preferred way of constructing filenames is to use FULLFILE. In this case, you could do
fn = fullfile('/home/alekhine', [num2str(i), '.dat']);
FULLFILE is preferred because it understands the different file separators on different OS types (i.e. \ on Windows and / on UNIX/Mac).
You seem to be missing a path separator in the path generation:
fn = ['/home/alekhine' num2str(i) '.dat'];
Should be:
fn = ['/home/alekhine/' num2str(i) '.dat'];
Related
I am studying Suever's answer where I do not understand its application with fullfile in Code 1.
Code 1
filename=strcat('/Users/masi/Images/', 'p.1');
save(fullfile(filename,'.mat'),'time');
saveas(her, fullfile(filename,'.png'));
Output
Error using save
Cannot create '.mat' because '/Users/masi/Images/p.1' does not
exist.
Code 2
filename=strcat('/Users/masi/Images/', 'p.1');
save(strcat(filename,'.mat'),'time');
saveas(her, strcat(filename,'.png'));
Success!
Change made based on Daniel's answer
filenameMat=fullfile('/Users/masi/Images/', 'p.1', '.mat');
save(filenameMat,'time');
but still getting
Error using save
Cannot create '.mat' because '/Users/masi/Images/p.1.mat' does not
exist.
I do not understand.
Why is code 1 giving the error?
You are using fullfile for a wrong application. The documentation clearly explains the parameters:
Folder and file names, specified as strings and cell arrays of strings.
You input a filename without extension and a file extension, hat is not what fullfile is made for. It will insert a file separator between both:
>> fullfile('foo','.bar')
ans =
foo\.bar
fullfile would be the right function to construct filename.
I want to save the value of a variable from MATLAB command history in a text. I am trying the command:
Save([d:/work/abc.txt], 'z1', '-ASCII');
An error appears
Error: input charecter is not valid in MATLAB environment or expression.
What you are missing are the quotes within the brackets for denoting string.
['string']
You should use save (with lower case for "s").
Also the filename should be defined as a string: enclose it withi two '; also you do not need the [] unless, for example, you want to build a string using a variable and / or any function to create part of the filename (e. g.
['d:/work/abc_' num2str(k) '.txt']
assuming k value is 3) to get d:/work/abc_3.txt
Try change your code to:
save(['d:/work/abc.txt'], 'z1', '-ASCII');
Hope this helps.
Qapla
I'm trying to export a matrix f that is double. My data in f are real numbers in three columns. I want a txt file as an output with the columns separated by tabs. However, when I try the dlmwrite function, just the first column appears as output.
for k = 1:10
f = [idx', firsttime', sectime'];
filename = strcat(('/User/Detection_rerun/AF_TIMIT/1_state/mergedlabels_train/'),(files_train{k,1}),'.lab');
dlmwrite(filename,f,'\t') ;
end
When I use dlmwrite(filename,f,'\t','newline','pc') ; I keep getting an error Invalid attribute tag: \t . I even tried 'tab' instead of '\t' but a similar error appears. Please let me know if you have any suggestions. thank you
This is because you are not calling dlmwrite properly. To specify the delimiter, you must use the delimiter flag, followed by the specific delimiter you want. In your case, you use \t. In other words, you need to do this:
for k = 1:10
f = [idx', firsttime', sectime'];
filename = strcat(('/User/Detection_rerun/AF_TIMIT/1_state/mergedlabels_train/'),(files_train{k,1}),'.lab');
dlmwrite(filename,f,'delimiter','\t') ;
end
BTW, you are using the newline flag with pc, meaning that you are specifying carriage returns that are recognized by a PC. I suggest you leave this out and allow MATLAB to automatically infer this. Only force the newline characters if you know what you're doing.
FWIW, the MATLAB documentation is pretty clear about delimiters and other quirks about the function: http://www.mathworks.com/help/matlab/ref/dlmwrite.html
I'm quite new to Matlab and programming in general and would love to get some help with the following. I've look here on the website, but couldn't find an answer.
I am trying to use a for-loop and fprintf to give me a bunch of separate text files, whose file names contain the index I use for my for-loop. See for example this piece of code to get the idea of what I'd like to do:
for z=1:20
for x=1:z;
b=[x exp(x)];
fid = fopen('table z.txt','a');
fprintf(fid,'%6.2f, %6.2f\n',b);
fclose(fid);
end
end
What I'm looking for, is a script that (in this case) gives me 20 separate .txt files with names 'table i.txt' (i is 1 through 20) where
table 1.txt only contains [1, exp(1)],
table 2.txt contains [1, exp(1)] \newline [2, exp(2)]
and so on.
If I run the script above, I get only one text file (named 'table z.txt' with all the data appended underneath. So the naming of fopen doesn't 'feel' the z values, but interprets z as a letter (which, seeing the quotation marks doesn't really surprise me)
I think there must be an elegant way of doing this, but I haven't been able to find it. I hope someone can help.
Best,
L
use num2str and string concatenation [ ... ].
fid = fopen( ['table ' num2str(z) '.txt'],'a');
Opening your file in the innermost loop is inefficient, you should create a file as soon as you know z (see example below). To format a string the same way that fprintf, you can use sprintf.
for z=1:20
fname = sprintf('table %d.txt',z);
fid = fopen(fname,'w');
for x=1:z
fprintf(fid,'%6.2f, %6.2f\n', x, exp(x));
end
fclose(fid);
end
%select all .mat files
oar = dir('*oar.mat'); n = {oar.name};
%loop through files
for l=1:length(oar);
load pat_oar(l) %<---this is the .mat file with variable filename
clear ...
end
How do I write some Matlab script that will read in one .mat file after another...
You file names are stored in n, so you should be able to do:
for l=1:length(oar)
load(n{l})
end
Use the functional form. Instead of:
load pat_oar{I}
Use
load(pat_oar{I})
Calling a Matlab command using the unix-style syntax (i.e. command arg1 arg2) is just syntax shorthand for the more verbose syntax of command('arg1','arg2'). It's a pretty common trick to use the more verbose syntax anytime an argument is stored in a variable.