May be my tired eyes are ignoring something trivial. But I am not able to get the following code work in matlab. I need to open an existing file and write text to it.
filename='E:\\data_bak\\test.txt';
fileId=fopen(filename,'r+');
if(fileId~=-1)
myline=fgetl(fileId);
nbytes=fprintf(fileId,'%s\n','testdata')
fclose(fileId);
end
I am using matlab 7.9.0 on windows 7. I have tried rt+ for permissions in fopen. Also, fileId is not equal to zero as I am able to read the line in the variable myline. In addition, fprintf('%s\n','testdata') successfully prints testdata on the matlab prompt.
The value assigned to nbytes is 9. So it does appear it has written to file but when I open the file in text editor, I am not able to find text 'testdata'.
Related
I've been trying to make the output shown in the text file instead of the command window. Im blur right now as i already look at a lot of example but it always show the error on fprintf. I try to edit the code of fprintf(fid,'%s\n',word);%Write 'word' in text file (upper) in one of the Matlab example which is Automatically Detect and Recognize Text in Natural Images.
This is the link of the code.
https://www.mathworks.com/help/vision/examples/automatically-detect-and-recognize-text-in-natural-images.html?s_tid=srchtitle
Basically the above link display the output on the command window. But, i need it to be on the txt file.
Im really new to this, i want to know what code do i need to put, how and where should i put the fprintf to make the output shown on the text file and not on the command window.
Also, can i save the text file after that? do i to put any additional code?
I really need your help. Thank u in advance!
It seems you're looking for the fopen() method. It takes two parameters, the first being the name of the file you'd like to write to, and the second being the mode. If the file specified does not exist in the root directory, it will be created on execution.
fileID = fopen('exp.txt','w');
fprintf(fileID, fid,'%s\n', word);
fclose(fileID); % Make sure to always close the stream after finishing
More on fopen() here
I'm just trying to import a csv file into Matlab using the textscan function. But everytime i run the program it always throws back this error
Error using textscan
Invalid file identifier. Use fopen to generate a
valid file identifier.
But as you can see in the code below i'm using fopen to prepare the file for the use of textscan.
S = 'Proto2.csv';
fidi = fopen(S);
C = textscan(fidi, '%f%s%f%f%f%f%f%f%s%f%f%f%f%f%f%f%f%f%f%f%f%f%f', 'Delimiter','\n', 'HeaderLines',11, 'CollectOutput',1);
Afterwards i'm using C to get access to data i need out of the csv file
Normally, before proceeding with reading and/or writing operations on a file handle, you must make sure that the handle returned by the fopen function is valid. From the official documentation of Matlab:
fileID = fopen(filename) opens the file, filename, for binary read
access, and returns an integer file identifier equal to or greater
than 3. MATLAB® reserves file identifiers 0, 1, and 2 for standard
input, standard output (the screen), and standard error, respectively.
If fopen cannot open the file, then fileID is -1.
Check your fidi variable value before proceeding with textscan, I'm pretty sure it is equal to -1. This happens either because the file is not found (if you don't specify a full absolute path, Matlab searches for it within the current working directory) or because the file has a sharing lock on it (hence, make sure that it's not being used by other applications while you attempt to read it).
I have written a simple textfile using notepad, and I placed the text file in the same folder as a matlab script I want to run. I pretty much want to make a script so that when the user clicks run a pop-up of my text file will come up purely within matlab.(I will later include separate figures, graphs to pop up at the same time.)
I tried researching, and I found fopen. But when I do fopen('FileName.txt','r'); nothing happens?
I am not sure of what you are looking for, but I guessed that you need to open a file and read its content using Matlab.
fid = fopen('FileName.txt','r'); % generate a file identifier
if fid < 0
error 'Unable to open file ... check file location'
else
while ~feof(fid) % while there is a line to read
disp(fgets(fid))
end
end
fclose(fid);
i am still working at my project and i again i hit a wall.
In this case i am trying to open a .pdf file from uimenu, i have searched through functions, i think i found the right one:
x = 'D:\MATLAB\Author.pdf';
y = 'D:\MATLAB\Bibliography.pdf';
f=uimenu('Label','ProjectData');
uimenu(f,'Label','Author','Callback','fopen(x)');
uimenu(f,'Label','Bibliography','Callback','fopen(y)');
uimenu(f,'Label','Close','Callback','close',...
'Separator','on','Accelerator','Q');
But the problem is that when i click on author or bibliography nothing happens, no errors, nothing.
The only thing that appears in command window is this :
ans =
-1
The .pdf files are in the same folder as the rest of the .m files.
Please help, Thank you !
That's because MATLAB can't open your file.
From the fopen documentation (available here) (the bold font is from me):
fileID = fopen(filename) opens the file, filename, for binary read
access, and returns an integer file identifier equal to or greater
than 3. MATLAB® reserves file identifiers 0, 1, and 2 for standard
input, standard output (the screen), and standard error, respectively.
If fopen cannot open the file, then fileID is -1.
So MATLAB is giving this fileID of -1. If you want MATLAB to open the appropriate application for your pdf file (i.e. Adobe Acrobat), you can use open.
If you want to actually open pdf as images in MATLAB, there is probably some function on the File Exchange.
Hope that helps!
This is a script written by someone else, and I don't understand why it is giving me this error (I don't really know Matlab, but this appears to be a fairly straightforward script, so I'm a bit stumped).
The file starts with
clear all
filein=['Runs/'];
Namein1=['AIC'];
Nameout=['Nash'];
It then does a bunch of calculations to get Nash-Sutcliffe coefficients (not important for this issue) and then tries to write the results to one file:
%Write Nash
%Output file writing
%Write file header
D={'Conbination','Nash with Error','Nash-error','RMSE','RMSE-error',...
'AIC', 'MinNash', 'MaxNash'};
NameOut=[filein,Nameout, '.txt'];
fileID = fopen(NameOut,'w');
for i=1:length(D)-1
fprintf(fileID,'%s\t',D{i});
Then more stuff follows, but this is where I get the error message:
Error using fprintf
Invalid file identifier. Use fopen to generate a valid file identifier.
Error in Nash_0EV_onlyT (line 169)
fprintf(fileID,'%s\t',D{i});
I don't get what is wrong here? The script specifies the file, and uses fopen...? Isn't it supposed to create the file Nash.txt with the fopen statement (this file currently does not exist in my folder Runs/)? What am I missing? Thanks!
PS I am running Matlab2013a (group license via the university) on a MacBook Pro with OSX 10.8
Try using fclose all before calling this script again. Often when testing, the file handle is never released (an error occurs before the file is closed), causing fopen on the same file to fail.
The better way to do this would be to use a more fail-safe construct:
NameOut = [filein Nameout '.txt'];
fileID = fopen(NameOut,'w');
if fileID > 0
try
for i = 1:length(D)-1
fprintf(fileID,'%s\t',D{i});
end
fclose(fileId);
catch ME
fclose(fileId);
throw(ME);
end
else
error('Error opening file.');
end
I am running Win 10 and matlab 2015a, but it happens in mine too.
finally, I realise that the matlab.exe can't write file in the folder /../bin/
so, change to
Nameout=['C:\Users\yourname\DesktopNash'];
try it, then tell me what' going on.
Okay, so as I said, I don't know Matlab... I hadn't properly specified the path for writing! So it was reading the input but I guess didn't know where to write to. Thanks for the answers, it did help me narrow down the problem!