Launching a very complex command in a Python program

Question

Inside a Python program I need to launch a complex command, indeed a python program that needs lots of arguments. What I need to launch is something like this:

./calculations.py -id -k "{'names':['r','pst'],'index_IN':['at','gl'],'index_OUT':[1,1]}"

                      -r "[False,False]" -N "[False,False]" -c "['values1**2','np.exp(values2)']"

                       $SCRATCH/my_dir/*

(Indeed, it's even more complex, but the main ideas are in this example).

So, the key points are the presence of both " and ' in the example, and the use of calculation (square numbers and exponentiation with numpy). I have tried subprocess.Popen but somehow I can't get it to work. My attempt:

proc = subprocess.Popen(["./calculations.py -id", "-k", 

       "{'names':['r','pst'],'index_IN':['at','gl'],'index_OUT':[1,1]}"], ........])

Thanks.

Answer 1

You can save strings as raw string in python with the r prefix, if you need both ' and " than consider using a raw long python string:

cmdAttributes = r"""{'names':['r','pst'],'index_IN':['at','gl'],'index_OUT':[1,1]}"""

So same thing with flexible entries:

pnames = r"['r','pst']"
pindex_IN = r"['at','gl']"
pindex_OUT = r"[1,1]"

cmdAttributes = r"""{{'names':{Names},'index_IN':{Index_IN},'index_OUT':{Index_OUT} }}""".format(
        Names = pnames,
        Index_IN = pindex_IN,
        Index_OUT = pindex_OUT)

cmdAttributes will be the same for both codes.