I have looked extensively in the net, yet not found exactly what I want.
I have a big simulation program that outputs results in a MATLAB M-file (let's call it res.m) and I want to plot the results visually.
I want to start the simulation with C++ many times in a row and therefore want to automatize the plotting of the results.
I come up to two options:
Execute from C++ an Octave or MATLAB script that generates the graph.
-> Haven't found anyone who managed to do so
Use the Octave source files to read the res.m file and output them after with whatever plotting C++ tool.
-> Theoretically possible but I get lost in those files
Is someone able to solve this? Or has a better, easier approach?
The answer is to execute through the terminal.
I didn't manage to actually run a octave script from my c++ program directly, but there is a way around messing with/through the terminal and a extra Octave file. I used in my cpp:
string = "octave myProgr.m"
const char *command = str.c_str();
system(command);
myProgr.m is the script that plots the res.m file
Related
I know how to do stuff with Lua states and what not but what i don't understand is how you would distribute the final program with a seperate lua file because say you have a .exe and a lua file in the same directory how would I make it so that it is all one executable like how Löve 2d uses
copy /b
to append the lua file to the Löve 2d interpreter so it can be distributed.
could someone possibly explain how this works.
many thanks
Blazing
You could embed the lua code directly into your C++ source in a raw string literal like so:
const auto lua_code = R"lua(
...lua code here...
)lua";
I'm having some trouble getting Matlab to run an executable file. Essentially, I have a C++ code that does some calculations and outputs these calculations to a text file; then, Matlab reads these text files and uses the calculations to makes plots and stuff.
I've been trying to get Matlab to run the C++ exe file so that, when it runs it, the output files are automatically generated and Matlab can start doing its stuff. This just allows the user to run the program quicker. I am using the system() command Like so:
system('MyCppProgram.exe');
However, when I run that, although everything compiles, nothing is outputted from CPP and I even get back something that says "ans = -1" and I have no idea what that means.
Any help would be greatly appreciated. Thank you!
Update: Result from test command.
[status, cmdout] = system('MyCppProgram.exe', '-echo');
status = -1
cmdout = ''
I am doing image analysis using C++ in the QtCreator environment. In order to build a learning model, I want to use the TreeBagger class from MATLAB, which is really powerful. Can I call MATLAB from QtCreator, give it some parameters, and get back the classification error? Can I do this without using mex files?
From QProcess's Synchronous Process API example:
QProcess gzip;
gzip.start("gzip", QStringList() << "-c");
if (!gzip.waitForStarted())
return false;
gzip.write("Qt rocks!");
gzip.closeWriteChannel();
if (!gzip.waitForFinished())
return false;
QByteArray result = gzip.readAll();
The concept to from this example is the process of being able to execute matlab w/ whatever settings that would be preferable and begin writing a script to it immediately. After the write; you can close the channel, wait for response, then read the results from matlab. Uunfortunately, I'm not experienced w/ it to provide a more direct example, but this is the concept for the most case. Please research the documentation for anything else.
Matlab has an "engine" interface described here to let standalone programs call matlab functions. It has the advantage that you can call engPutVariableand engGetVariable to transfer your data in binary format (I think it works by using shared memory between your process and matlab, but I'm not sure on this), so you don't have to convert your data to ascii and parse the result from ascii.
For c++ you might want to write a wrapper class for RAII or have a look at http://www.codeproject.com/Articles/4216/MATLAB-Engine-API, where this has already been done.
How do I execute a R command in C, without using R extensions, something like:
int main() {
system("R g<- graph(c(0,1,0,4,0,9,1,7,1,9,2,9,2,3,2,5,3,6,3,9,4,5,4,8,5,8,6,7,6,8,7,8),n=10,dir=FALSE)
plot(g)")
return(0)
}
You can run R using the system() call as you have, but you can't stick R functions on the command line like that.
What you can do is to write the R code to a file and call it with system("R CMD BATCH foo.R") - minimally:
main(){system("R CMD BATCH test.R");}
Now, by default the output graphics from R CMD BATCH go to a PDF file, so you need to open a graphics window and make the script pause if you want to see it.
Of course your test.R file could be written by your C code before it runs it, and you could keep it in a temporary directory or something.
An alternative for R CMD BATCH is Rscript. I think for problems where C++ and R are not tightly integrated, i.e. there are distinct phases where R and C++ are used, nor large volumes or frequency of data exchange, using system calls can be very simple and robust.
An alternative is to run R and C++ alongside each other and exchange info between them. This can be done using the RInside pacakge, which is available on CRAN.
I have a QT C++ application that runs the Octave program using QProcess. I am able to communicate with it by reading the standard output/error and writing to it's standard input using write method (for example: octave->write("5 + 5\n");).
As I told you I get response from octave (from the above example I get "ans = 10").
However, when the command I write to Octave standard input has a "plot" (for example, a simple plot([1 2 3 4 5]);), the actual graphic is never shown. I know Octave runs gnuplot, I have it installed, and gnuplot_x11 too. I even change the gnuplot binary path in my Octave process by executing gnuplot_binary("/usr/bin/gnuplot"); from MY APPLICATION. I know it runs good because if I retrieve the new value I get it right. But I don't know why Octave doesn't show the graphic.
Here I start octave:
QStringList arguments;
arguments << "--persist";
octave->setProcessChannelMode(QProcess::MergedChannels);
octave->start("/usr/bin/octave", arguments);
Here I write commands to octave process:
if (octave->state() == QProcess::Running) {
QString command = widget.txtInput->toPlainText();
if (command.isEmpty()) {
return;
}
command += "\n";
octave->write(command.toAscii());
}
With this I print the octave response to a text edit:
widget.txtOutput->append(octave->readAll() + "\n");
And finally, I use this when the octave process starts:
QString gnuplot_path(tr("\"/usr/bin/gnuplot\""));
QString gnuplot_cmd(tr("gnuplot_binary(%1)\n").arg(gnuplot_path));
octave->write(gnuplot_cmd.toAscii());
I will appreciate any help you could give me.
Thanks in advance.
Octave, like Matlab, can be run in batch mode to perform computations without graphical UI. I assume that Octave detects that it is not run from an interactive session, and therefore automatically goes into batch mode. You would expect Octave to suppress graphical output (e.g. gnuplot output) when being in batch mode.
Try to force Octave into interactive mode by using the --interactive command line option:
http://www.gnu.org/software/octave/doc/interpreter/Command-Line-Options.html
I know you probably already solved your problem but this might be helpful for other...
You can try to add a command to save your plot in a temporary folder in your octave request.
Then display the graph in your ap