DRIVER.py

import time
start_time = time.time()
from openmdao.api import Problem, Group, IndepVarComp
from openmdao.api import  ScipyOptimizeDriver
from WRAPPER import WRAPPER
top = Problem()
top.model = model = Group()
# <codecell>
inputs_comp = IndepVarComp()
inputs_comp.add_output('DV1',  3)
inputs_comp.add_output('DV2',  1)
inputs_comp.add_output('DV3', 17.0)
# <codecell>
" Add components/subsystems to the Group-model- "
model.add_subsystem('inputs_comp', inputs_comp)
model.add_subsystem('WRAPPER', WRAPPER())

model.connect('inputs_comp.DV1', 'WRAPPER.DV1')
model.connect('inputs_comp.DV2', 'WRAPPER.DV2')
model.connect('inputs_comp.DV3', 'WRAPPER.DV3')

# <codecell>
"Select driver and optimizer set driver options. "
top.driver = ScipyOptimizeDriver()
top.driver.options['optimizer'] = 'SLSQP'
#top.driver.options['optimizer'] = 'COBYLA'
top.driver.options['tol'] = 1e-4
top.driver.options['disp'] = True
# <codecell>
" Select design variables and their range "
top.model.add_design_var('inputs_comp.DV1', lower=-2, upper=8)
top.model.add_design_var('inputs_comp.DV2', lower=-5, upper=2)
top.model.add_design_var('inputs_comp.DV3', lower=16, upper=20)
# <codecell>
top.model.add_objective('WRAPPER.OBJ',scaler=-1)

top.setup()
top.setup(check=True, mode='rev')

top.run_driver()

print(top['inputs_comp.DV1'])
print(top['inputs_comp.DV2'])
print(top['inputs_comp.DV3'])
print("--- %s seconds ---" % (time.time() - start_time))

WRAPPER.py

from openmdao.api import ExternalCode
import numpy as np
class WRAPPER(ExternalCode):
    def setup(self):
        self.add_input('DV1')
        self.add_input('DV2')
        self.add_input('DV3')   

        self.add_output('OBJ')
		
        self.input_file  = 'WRAPPER_input.dat'
        self.output_file = 'WRAPPER_output.dat'

        # providing these is optional; the component will verify that any input
        # files exist before execution and that the output files exist after.
        self.options['external_input_files'] = [self.input_file,]
        self.options['external_output_files'] = [self.output_file,]

        
        self.options['command'] = [
            'python', 'gf_run.py', self.input_file, self.output_file
        ]
        self.declare_partials(of='OBJ', wrt=['DV1','DV2','DV3'], method='fd',form='central', step=1e-4)

    def compute(self, inputs, outputs):
        DV1 	 = inputs['DV1']
        DV2 	 = inputs['DV2']
        DV3 = inputs['DV3']
        # generate the input file for the paraboloid external code
        np.savetxt(self.input_file,[DV1,DV2,DV3])
        # the parent compute function actually runs the external code
        super(WRAPPER, self).compute(inputs, outputs)
        # parse the output file from the external code
        file_contents=np.loadtxt(self.output_file)

        outputs['OBJ'] 			  = file_contents[0]