I'm having troubles opening a file with different fid that is previously opened with 'Input'.
Example:
fid1=fopen((input('Video: ')),'r');
fid2=fopen((input('Save as: ')),'w');
...
...
fid3=fopen('','r'); % Here I want to open the input video same as fid1
I don't know how to request returned value, in this case the name entered.
Entering fid3=fid1 after declaration of fid1 does not help me.
I don't want to ask for the name to be input again (I.e fid3=fopen((input('Video: ')),'r');).
To do what you want to do, you need to capture and store the filename somewhere. I really don't think that information can be recovered from a file pointer.
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 want to save a matrix (e.g. "PTX_Data_Raw.mat") in another folder (e.g. Temp folder). I have written below code:
mkdir('D:\Projects\ProgrammingPart\Method2_FinalApproved\8-congruent','Temp');
filename=('D:\Projects\ProgrammingPart\Method2_FinalApproved\8-congruent\Temp');
save(filename,'PTX_Data_Raw.mat');
but it didn't work. Does anybody can help me for solving this problem?
THX
Going with your comments, you are using save wrong. The first parameter is the filename you want to call the MAT file and second parameter and onwards are the variables you want to save.
Therefore, you need to make sure filename contains the entire filename, including the path followed by the actual name of the MAT file you want. After, the second parameter is PTX_Data - the name of the matrix you want to save.
mkdir('D:\Projects\ProgrammingPart\Method2_FinalApproved\8-congruent','Temp');
%// Change
filename=('D:\Projects\ProgrammingPart\Method2_FinalApproved\8-congruent\Temp\PTX_Data_Raw.mat');
save(filename,'PTX_Data'); %// Change
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 have a MATLAB script that I could have sworn worked fine the last time I used it (a year ago). Now, I get this error:
Invalid file identifier. Use fopen to generate a valid file identifier.
If I understand correctly, it is failing to find or open(?) a file specified elsewhere in the script. Is this right? If so, what could cause it?
fid (file identifier) is the output of fopen. It's an integer, but not related to the file permanently. You need to use fopen to get the fid. It seems to me that you are using incorrect fid (file identifier) in some file-related I/O command, such as fread, fscanf or fclose. Unsuccessful fopen gives fid of -1. For any valid normal file successful fopen will give fid that is 3 or greater integer.
However, without any code it's impossible to say where or what the bug or error is. You could use MATLAB debugger to single-step the code from relevant fopen (set breakpoint there and run your program) until the relevant fclose and see if fid (or whatever variable name you use for file identifier) or any data structure for your file identifiers (if have more than one file identifier in your code) changes in any point between relevant fopen and fclose.
I solved this problem for my self by adding permission option to fopen.
As you see in http://www.mathworks.se/help/matlab/ref/fopen.html , fopen syntax is:
fileID = fopen(filename,permission)
Possible permissions, for example are:
'r' (default) | 'w' | 'a' | 'r+' | 'w+' | 'a+' | ...
'r' – Open file for reading.
'w' – Open or create new file for writing. Discard existing contents, if any.
'a' –
Open or create new file for writing. Append data to the end of the file.
'r+' – Open file for reading and writing.
'w+' – Open or create new file for reading and writing. Discard existing contents, if any.
'a+' – Open or create new file for reading and writing. Append data to the end of the file.
...
If I use fopen without permission option, or if I use 'r' (default) option, fopen will return -1, which is error. I success with this:
fid=fopen('tmp.txt', 'w');
fid=fopen('tmp.txt', 'a');
I had this problem. It turned out that the file I was trying to write was too large (I didn't have enough free space to accommodate it). However, the program didn't fail until the call to fclose. Very confusing!
Try freeing up some space, or writing a very small file, to test this diagnosis.
I encountered the same problem when trying to open ASF toolbox demos. Running Matlab as an administrator(right-click to open) seemed to solve this issue for me.
fopen can fail because MATLAB doesn't have the permissions to read/write the file you've specified.
Try opening a file in a location where you/MATLAB have all the rights (depending on your OS).
I have used fopen with permission and the same error came out. However, I started MATLAB as admin and that took care of the problem.
I had the file opened in excel and as a result fopen returned a -1.
Took me forever to find such a trivial problem.
It also happens when trying to create a file in a non-existent directory. Try mkdir('folderName') within MATLAB or just create the directory beforehand.
The path with a forward slash at the beginning can cause the same error.
filename = '/data/myfile.txt';
throws this error, while
filename = 'data/myfile.txt';
does not produce an error.
For my situation, I have checked everything, but missed an easy step.
Please select "browse your folder" and browse for your current document location before you run your 'fopen' code.
It also occurs when a script is trying to read beyond the end of the file.
I have a MATLAB script that I could have sworn worked fine the last time I used it (a year ago). Now, I get this error:
Invalid file identifier. Use fopen to generate a valid file identifier.
If I understand correctly, it is failing to find or open(?) a file specified elsewhere in the script. Is this right? If so, what could cause it?
fid (file identifier) is the output of fopen. It's an integer, but not related to the file permanently. You need to use fopen to get the fid. It seems to me that you are using incorrect fid (file identifier) in some file-related I/O command, such as fread, fscanf or fclose. Unsuccessful fopen gives fid of -1. For any valid normal file successful fopen will give fid that is 3 or greater integer.
However, without any code it's impossible to say where or what the bug or error is. You could use MATLAB debugger to single-step the code from relevant fopen (set breakpoint there and run your program) until the relevant fclose and see if fid (or whatever variable name you use for file identifier) or any data structure for your file identifiers (if have more than one file identifier in your code) changes in any point between relevant fopen and fclose.
I solved this problem for my self by adding permission option to fopen.
As you see in http://www.mathworks.se/help/matlab/ref/fopen.html , fopen syntax is:
fileID = fopen(filename,permission)
Possible permissions, for example are:
'r' (default) | 'w' | 'a' | 'r+' | 'w+' | 'a+' | ...
'r' – Open file for reading.
'w' – Open or create new file for writing. Discard existing contents, if any.
'a' –
Open or create new file for writing. Append data to the end of the file.
'r+' – Open file for reading and writing.
'w+' – Open or create new file for reading and writing. Discard existing contents, if any.
'a+' – Open or create new file for reading and writing. Append data to the end of the file.
...
If I use fopen without permission option, or if I use 'r' (default) option, fopen will return -1, which is error. I success with this:
fid=fopen('tmp.txt', 'w');
fid=fopen('tmp.txt', 'a');
I had this problem. It turned out that the file I was trying to write was too large (I didn't have enough free space to accommodate it). However, the program didn't fail until the call to fclose. Very confusing!
Try freeing up some space, or writing a very small file, to test this diagnosis.
I encountered the same problem when trying to open ASF toolbox demos. Running Matlab as an administrator(right-click to open) seemed to solve this issue for me.
fopen can fail because MATLAB doesn't have the permissions to read/write the file you've specified.
Try opening a file in a location where you/MATLAB have all the rights (depending on your OS).
I have used fopen with permission and the same error came out. However, I started MATLAB as admin and that took care of the problem.
I had the file opened in excel and as a result fopen returned a -1.
Took me forever to find such a trivial problem.
It also happens when trying to create a file in a non-existent directory. Try mkdir('folderName') within MATLAB or just create the directory beforehand.
The path with a forward slash at the beginning can cause the same error.
filename = '/data/myfile.txt';
throws this error, while
filename = 'data/myfile.txt';
does not produce an error.
For my situation, I have checked everything, but missed an easy step.
Please select "browse your folder" and browse for your current document location before you run your 'fopen' code.
It also occurs when a script is trying to read beyond the end of the file.