If I do x='bob:.mat' and then try to save it as a mat file like so:
number=10;
save(bob,'number');
I get an issue where it can't be saved, and I am assuming this is the case because: is a special character. I looked up online how to use it, and an example told me to put a ' mark before it, but that didn't work. Any help would be appreciated.
It should be: save('bob.mat', 'number');
Or
save bob number
save('bob', 'number'); also works.
save('bob:', 'number'); results an error (in Windows):
Error using save
Unable to open file "bob:" for output.
A file name with : is not allowed, because it's reserved for drive letters like C:.
A workaround is described here: How to get a file in Windows with a colon in the filename?
Following code actually does work:
save('bob꞉','number');
Related
I would like to save a workspace in another directory and I have written the following in Matlab for it:
fileName = [datestr(now, 'dd-mmm-yyyy_HHMMSS') '_test'];
save('C:\Users\User\project',fileName)
It gives me the error: Error using save: '05-Nov-2019_083736_test' is not a valid variable name.
But if I run without giving an address of the directory it workes perfectly.
Why does it happen?
You can either use il_raffa's suggestion from the comments (with a small correction):
save(['C:\Users\User\project\' fileName])
% ^ add a folder separator here
or use the fullfile function, to avoid errors due to forgotten folder separators:
save(fullfile('C:\Users\User\project', fileName));
This works also for subfolders and filenames, e.g.
save(fullfile('C:\Users\User\project', 'matfiles', fileName));
When I use the readtable function I get the following error:
IVcellData = readtable('RiskModelData','Sheet',2,'Range','A1:A49')
Error using readtable (line 129) Invalid parameter name: Sheet.
Would appreciate if anyone could help me.
Have you renamed Sheet 2 to something else, e.g. Datafile? If so, you need to use this name (inside single quotes) not the sheet number instead of 2 in that call.
Also, you need to make a call to
opts = detectImportOptions(yourfilename)
before the call to readtable. I suspect this one is this cause as it is not recognising Sheet as a variable.
Took me a while to discover that lot, mostly empirical as the documentation is not clear on that point.
Keith
Looks like you need to define extension:
T = readtable(filename) creates a table by reading column oriented data from a file.
readtable determines the file format from the file name's extension:
.txt, .dat, or .csv for delimited text files
.xls, .xlsb, .xlsm, .xlsx, .xltm, .xltx, or .ods for spreadsheet files
try ReadModelData.xls or .xlsx
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've noticed a strange behavior of Matlab when accessing files. Say I have a path to a file like this:
path = '~/data/file'
If I run exist(path), the result is 2, i.e. the file exists. If I run
textread(path, '%s')
then I get an error message
Error using dataread
File not found or permission denied.
However, if I expand the tilde and run textread, it works fine:
path2 = '/home/username/data/file'
textread(path2, '%s')
Can you explain this behavior?
Yes, exist understands relative paths (as identified by the tilde), whereas textread does not.
Note that textscan is now the preferred way of reading data from a file - this accepts file identifiers so will work with relative paths.
If this is not an option, a good GetFullPath function can be found here.
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.