I'm relatively new to using Octave. I'm working on a project that requires me to collect the RGB values of all the pixels in a particular image and compare them to a list of other values. This is a time-consuming process that takes about half a minute to run. As I make edits to my code and test it, I find it annoying that I need to wait for 30 seconds to see if my updates work or not. Is there a way where I can run the code once at first to load the data I need and then set up an artificial starting point so that when I rerun the code (or input something into the command window) it only runs a desired section (the section after the time-consuming part) leaving the untouched data intact?
You may set your variable to save into a global variable,
and then use clear -v instead of clear all.
clear all is a kind of atomic bomb, loved by many users. I have never understood why. Hopefully, it does not close the session: Still some job for quit() ;-)
To illustrate the proposed solution:
>> a = rand(1,3)
a =
0.776777 0.042049 0.221082
>> global a
>> clear -v
>> a
error: 'a' undefined near line 1, column 1
>> global a
>> a
a =
0.776777 0.042049 0.221082
Octave works in an interactive session. If you run your script in a new Octave session each time, you will have to re-compute all your values each time. But you can also start Octave and then run your script at the interactive terminal. At the end of the script, the workspace will contain all the variables your script used. You can type individual statements at the interactive terminal prompt, which use and modify these variables, just like running a script one line at the time.
You can also set breakpoints. You can set a breakpoint at any point in your script, then run your script. The script will run until the breakpoint, then the interactive terminal will become active and you can work with the variables as they are at that point.
If you don't like the interactive stuff, you can also write a script this way:
clear
if 1
% Section 1
% ... do some computations here
save my_data
else
load my_data
end
% Section 2
% ... do some more computations here
When you run the script, Section 1 will be run, and the results saved to file. Now change the 1 to 0, and then run the script again. This time, Section 1 will be skipped, and the previously saved variables will be loaded.
I have downloaded the "NYU Depth V2" dataset and toolbox from here. In the toolbox there is a script called get_synched_frames.m. I do not have Matlab, so I have tried running it in Octave. Unfortunately, it does not work as expected.
The line
% Faster than matlab's Dir function for big directories and slow
% distributed file systems...
files = regexp(ls(sceneDir), '(\s+|\n)', 'split');
gives only
files =
{
[1,1] = a-1300302776.479149-3987628315.dump
}
but ls(sceneDir) shows all files in the directory. Has anyone experienced this?
The difference is probably not in regexp, but in the return value of ls. ls does not behave the same way in Matlab and Octave when you capture its return value. Matlab's ls returns a char row vector (single string as char) with multiple files listed in it as a multi-line string with embedded newlines; Octave's ls returns a 2-D char array with one file per line. (IMHO Octave's format is better; it is very difficult to parse Matlab's ls output in a reliably correct manner. (That regexp code is not adequate.))
You might just want this in Octave:
files = cellstr(ls(sceneDir));
I am trying to use a formatted string to identify the file location when using 'print -dpdf file_name' to write a plot (or figure) to a file.
I've tried:
k=1;
file_name = sprintf("\'/home/user/directory to use/file%3.3i.pdf\'",k);
print -dpdf file_name;
but that only gets me a figure written to ~/file_name.pdf which is not what I want. I've tried several other approaches but I cannot find an approach that causes the the third term (file_name, in this example) to be evaluated. I have not found any other printing function that will allow me to perform a formatted write (the '-dpdf' option) of a plot (or figure) to a file.
I need the single quotes because the path name to the location where I want to write the file contains spaces. (I'm working on a Linux box running Fedora 24 updated daily.)
If I compute the file name using the line above, then cut and paste it into the print statement, everything works exactly as I wish it to. I've tried using
k=1;
file_name = sprintf("\'/home/user/directory to use/file%3.3i.pdf\'",k);
print ("-dpdf", '/home/user/directory to use/file001.pdf');
But simply switching to a different form of print statement doesn't solve the problem,although now I get an error message:
GPL Ghostscript 9.16: **** Could not open the file '/home/user/directory to use/file001.pdf' .
**** Unable to open the initial device, quitting.
warning: broken pipe
if you use foo a b this is the same as foo ("a", "b"). In your case you called print ("-dpdf", "file_name")
k = 1;
file_name = sprintf ("/home/user/directory to use/file%3.3i.pdf", k);
print ("-dpdf", file_name);
Observe:
>> k=1;
>> file_name = sprintf ('/home/tasos/Desktop/a folder with spaces in it/this is file number %3.3i.pdf', k)
file_name = /home/tasos/Desktop/a folder with spaces in it/this is file number 001.pdf
>> plot (1 : 10);
>> print (gcf, file_name, '-dpdf')
Tadaaa!
So yeah, no single quotes needed. The reason single quotes work when you're "typing it by hand" is because you're literally creating the string on the spot with the single quotes.
Having said that, it's generally a good idea when generating absolute paths to use the fullfile command instead. Have a look at it.
Tasos Papastylianou #TasosPapastylianou provided great help. My problem is now solved.
Hi I want to generate some random matrices of size Nx3 for varying N, in GNU-Octave. I want to save each of these matrices to a different file.
The script below almost does the job, but strangely it produces only file with the name int2str(N) ; it keeps overwriting the files produced at the previous iteration.
for i=1:10
N=(2**i)
A=rand(N,3);
save int2str(N) A
end
The script is interpreting int2str(N) itself as a string. How do I avoid this behaviour?
You can invoke save with the function form:
save(int2str(N), "A")
The Octave documentation on this subject is both intimidating and sparse.
I did not know where else to document the solution I found, so I am posting here. I apologize if that's inappropriate, but I want to help the next guy.
The following solution is for a simple windows distributable.
Use Case:
A solution is developed in Octave 3.2.4, and needs to be distributed to end-users with few computer skills. Installing and explaining Octave is impossible, the solution must be "one-click" or "brain-dead-simple."
Known Issues:
imread fails in 3.2.4 because file_in_path.m is wrong. You will need to update the file file_in_path.m to the following (just replace it):
function name=file_in_path(p,file)
idx=[1 findstr(p,pathsep) length(p)+1];
for i=1:length(idx)-1
if idx(i+1)-idx(i)<=1
dir=strcat(pwd,"/");
else
dir=p(idx(i)+1:idx(i+1)-1);
end
name = fullfile(dir, file);
fid = fopen(name,"r");
if fid >= 0
fclose(fid);
return
end
end
fid = fopen(file,"r");
if fid >= 0,
fclose(fid);
name=file;
return
end
name=[];
Solution: Create a distributable exe using mkoctfile, and package this exe with the core Octave files, and other .oct and .m files as necessary.
Step 1: Create a stand-alone executable.
You can see code that works here:
http://www.gnu.org/software/octave/doc/interpreter/Standalone-Programs.html
Particularly the file "embedded.cc".
I have simplified that file as follows:
#include <iostream>
#include <octave/oct.h>
#include <octave/octave.h>
#include <octave/parse.h>
int
main (int argc, char *argvc[])
{
string_vector argv (2);
argv(0) = "embedded";
argv(1) = "-q";
octave_main (2, argv.c_str_vec(), 1);
octave_value_list in = octave_value (argvc[1]);
octave_value_list out = feval ("your_custom_m_file", in);
if (!error_state && out.length () > 0)
{
}
else
{
std::cout << "invalid\n";
}
return 0;
}
Build this file with the command
mkoctfile --link-stand-alone embedded.cc -o embedded
It may throw warnings, but as long as it throws no errors, you should be fine. The file embedded.exe will be built, and can be run. The only issue is that it will lack all the goodies that make octave awesome. You will have to provide those.
Step 2: Create a distribution folder
You will need to create a copy of many of the Octave files. I suggest a directory specifically for this. At a minimum, you will need a copy of all or most of the DLLs in \bin. Additionally, place your distributable executable in this directory.
Step 3: Other files whack-a-mole
You will now need to find out what other files will be necessary to run your .m script. You can simplify this step by copying \oct\i686-pc-mingw32*.oct and \share\octave\3.2.4\m\*\*.m to the distribution directory, although this will be overkill, and will not actually prevent the whack-a-mole step.
Now, you must play whack-a-mole or the time-honored tradition of "where my includes be at, yo?"
Open a cmd prompt and navigate to your distribution folder.
Get rid of any useful PATH strings. Your customers won't have them.
Attempt to run the program embedded.exe. You will get an error such as the following:
embedded.exe
error: `max' undefined near line 83 column 22
error: evaluating argument list element number 1
error: evaluating argument list element number 1
error: called from:
error: T:\sms\Development\research\c2\disttest\strcat.m at line 83, column 3
error: T:\sms\Development\research\c2\disttest\file_in_path.m at line 5, column 10
error: T:\sms\Development\research\c2\disttest\imread.m at line 50, column 6
A Search in your Octave installation for "max". It will either be a .oct or a .m file. In this case, it is a .oct file, max.oct. Copy it to your distribution directory.
B You search for something obvious like "min", and get no results. This is because the Loadable Function "min" is in the .oct file "max.oct". Make a copy of max.oct, and rename it to min.oct. It will work now. How do you know where the functions are? I'm not sure. Most of them are in obvious places like "max.oct" for min, and "fft2.oct" for "ifft2.oct". Good luck with all that.
Repeat until your executable runs.
Just to add that if you want to run a script instead of an m function, then the line of the embedded.cc:
octave_value_list out = feval ("your_custom_m_file", in);
should be:
octave_value_list out = feval ("your_custom_m_script");
Also use 'which' to find where the missing functions are packed. For example for the min function:
octave:22> which min
min is a function from the file C:\Octave\Octave3.6.2_gcc4.6.2\lib\octave\3.6.2\oct\i686-pc-mingw32\max.oct
Something I found when linking my custom m file into an Octave standalone:
Needed #include <octave/toplev.h>
Replace return 0; (as above) with clean_up_and_exit(0);
Without these steps my program repeatedly crashed on exit.
Run mkoctfile --link-stand-alone embedded.cc -o embedded
from the octave solution and not from a batch file.
Just saved you half day (-;
In the above solution in bullet 4 B:
B You search for something obvious like "min", and get no results.
This is because the Loadable Function "min" is in the .oct file
"max.oct". Make a copy of max.oct, and rename it to min.oct. It will
work now.
This might not work if some function is being called from #folder function.m and also to avoid unnecessary duplicated files, just add the following code somewhere in your m file outside #folder
autoload ("min", "max.oct");
Likewise, it can be removed via
autoload ("min", "max.oct", "remove");
Ensure that the path to max.oct is provided here.
The above understanding is based on a file PKG_ADD and PKG_DEL in the communications package located at \Octave-4.0.1\lib\octave\packages\communications-1.2.1\i686-w64-mingw32-api-v50+\
Check out Stratego Octave Compiler.
(I've not tested it yet, but plan to do so in the next few days.)
I had that very same requirement (one-click, brain-dead-simple), so I made a setup that contained only curl.exe, the batch file below, an exe which was a .bat in disguise (simply calling the batch file below) and the .vbs script below (not writen by me). And of course my m-file.
This will download Octave 4.2.1 as a portable program (32 bit, otherwise we'dd have to download again if the system turns out to be 32 bit), unpack using the vbs script, move the contents to the same folder as the batch file and run it in GUI mode. Every next time the same script is called, it will only check if octave.bat is still there.
Of course this results in a huge waste of disk space, downloading the 280MB zip, which unpacks to over 1GB (which I make even worse by not deleting the zip afterwards), and you're stuck with a cmd window that is not easy to hide.
But it does offer the simplest solution I could find. It is also less likely to break in the future (either with an update of your own, or an update from Octave). Some glorious day, mkoktfile will actually be easy to use and will solve dependencies on its own, but until that day this remains the least headache-inducing solution I could find. And aspirins are more expensive than someone else's disk space.
::this file will test if the octave portable is downloaded and unpacked
#ECHO OFF
SET my_m_file=your_mfile.m
SET name_of_this_script=run_me.bat
::if the file exists, skip to the actual running.
IF EXIST "octave.bat" goto OctaveIsExtracted
IF EXIST "octave-4.2.1-w32.zip" goto OctaveIsDownloaded
ECHO The runtime (Octave portable 4.2.1) will now be downloaded.
ECHO This may take a long time, as it is about 280MB.
ECHO .
ECHO If this download restarts multiple times, you can manually download the octave-4.2.1-w32.zip from the GNU website. Make sure to unpack the contents.
::if this errors, you can uncomment the line with archive.org (which doesn't report total size during download)
curl http://ftp.gnu.org/gnu/octave/windows/octave-4.2.1-w32.zip > octave-4.2.1-w32.zip
::curl http://web.archive.org/web/20170827205614/https://ftp.gnu.org/gnu/octave/windows/octave-4.2.1-w32.zip > octave-4.2.1-w32.zip
:OctaveIsDownloaded
::check to see if the file size is the correct size to assume a successful download
::if the file size is incorrect, delete the file, restart this script to attempt a new download
::file size should be 293570269 bytes
call :filesize octave-4.2.1-w32.zip
IF /I "%size%" GEQ "293560000" goto OctaveIsDownloadedSuccessfully
del octave-4.2.1-w32.zip
::start new instance and exit and release this one
start %name_of_this_script%
exit
:OctaveIsDownloadedSuccessfully
IF EXIST "octave.bat" goto OctaveIsExtracted
::unzip and move those contents to the current folder
ECHO Unzipping octave portable, this may take a moment.
cscript //B j_unzip.vbs octave-4.2.1-w32.zip
SET src_folder=octave-4.2.1
SET tar_folder=%cd%
for /f %%a IN ('dir "%src_folder%" /b') do move %src_folder%\%%a %tar_folder%
pause
:OctaveIsExtracted
octave.bat %my_m_file%
goto :eof
:filesize
set size=%~z1
exit /b 0
And j_unzip.vbs
' j_unzip.vbs
'
' UnZip a file script
'
' By Justin Godden 2010
'
' It's a mess, I know!!!
'
' Dim ArgObj, var1, var2
Set ArgObj = WScript.Arguments
If (Wscript.Arguments.Count > 0) Then
var1 = ArgObj(0)
Else
var1 = ""
End if
If var1 = "" then
strFileZIP = "example.zip"
Else
strFileZIP = var1
End if
'The location of the zip file.
REM Set WshShell = CreateObject("Wscript.Shell")
REM CurDir = WshShell.ExpandEnvironmentStrings("%%cd%%")
Dim sCurPath
sCurPath = CreateObject("Scripting.FileSystemObject").GetAbsolutePathName(".")
strZipFile = sCurPath & "\" & strFileZIP
'The folder the contents should be extracted to.
outFolder = sCurPath
'original line: outFolder = sCurPath & "\"
WScript.Echo ( "Extracting file " & strFileZIP)
Set objShell = CreateObject( "Shell.Application" )
Set objSource = objShell.NameSpace(strZipFile).Items()
Set objTarget = objShell.NameSpace(outFolder)
intOptions = 256
objTarget.CopyHere objSource, intOptions
WScript.Echo ( "Extracted." )