Python不等待MATLAB完成

Question

I am interfacing a small MATLAB script with Python via the subprocess module. As follows:

cmd='(matlab -nosplash -nodesktop -r "optimizer;quit;")'
p = subprocess.Popen(cmd,stdin=None,stdout=None,shell=True)
#subprocess.Popen.wait(p)
#p.wait()
print "DONE?"

But "DONE" is being printed even before MATLAB starts! My entire code past it is breaking because of this.

I have tried:

• Using os.system() calls (This is where I started, but I read on SO that its deprecated)
• Using p.wait() and subprocess.Popen.wait . Both don't work.
• Using a manual pause of 3 minutes (Max. time MATLAB takes to finish on average) Super Sloppy .

What am I missing?

Answer 1

Works fine for me:

import subprocess
retcode = subprocess.call(["matlab", "-nosplash", "-nodesktop", "-r", "quit;"])
print "DONE", retcode

Split the command arguments accordingly, use only options that you actually require (no need for shell=True , for example), use the function that directly does what you are after ( call ), ie, call and wait for completion.

Depending on your installation (see http://www.mathworks.com/help/matlab/ref/matlabwindows.html ), Matlab may be launched in a way such that it immediately quits. To handle that, add "-wait" to your argument list.

Answer 2

Start Matlab with the "-wait" flag. From the documenation:

"MATLAB is started by a separate starter program which normally launches MATLAB and then immediately quits. Using this option tells the starter program not to quit until MATLAB has terminated. This option is useful when you need to process the results from MATLAB in a script. Calling MATLAB with this option blocks the script from continuing until the results are generated."

Answer 3

Based on your response to my comment, let me answer your question with what I did for my application, that had a similar process to yours (albeit in C#). Instead of trying to force your process to wait for MATLAB to finish up (which is obviously not working right now), just wait for that CSV file to be written to. If you're worried about possibly having duplicates, then just append the current date and time to the end of the file, and that should do the trick.