python - 如何向 openmdao 驱动程序添加整数变量？

Question

我对这个 openmdao 错误感到困惑。为什么会提出这个问题？我可以以某种方式告诉 openmdao 我没有梯度并使用有限差分吗？为什么针对 childWeight 提高此值，而不针对 eta 提高？

我可以通过将所有变量初始化为浮点来解决这个问题(例如root.add('childWeight', IndepVarComp('x',100)) -> root .add('childWeight', IndepVarComp('x',100.0)))，但我想了解为什么会出现此错误。

from openmdao.api import Component, Group, Problem, ScipyOptimizer, IndepVarComp

class gym(Component):
    def __init__(self):
        super(gym, self).__init__()
        self.add_param('eta', 0.01)
        self.add_param('childWeight', 240)

        self.add_output('acc', 1)

    def solve_nonlinear(self, params, unknowns, resids):
        <...... parameters are used to produce objective "acc" ...>
        unknowns["acc"] = ....

top = Problem()
root = top.root = Group()
root.add('gym', gym())
top.driver = ScipyOptimizer()
top.driver.options['optimizer'] = 'BFGS'

root.add('eta',IndepVarComp('x', 0.01))
root.add('childWeight', IndepVarComp('x',100))

root.connect('eta.x', 'gym.eta')
root.connect('childWeight.x', 'gym.childWeight')

top.driver.add_desvar('eta.x', 0, 1.0)
top.driver.add_desvar('childWeight.x', 0, 1000)

top.driver.add_objective('gym.acc')
top.setup()
top.run()

引发错误

  File "script.py", line 98, in <module>
    top.setup()
  File "/usr/local/lib/python2.7/site-packages/openmdao/core/problem.py", line 694, in setup
    self.driver._setup()
  File "/usr/local/lib/python2.7/site-packages/openmdao/drivers/scipy_optimizer.py", line 91, in _setup
    super(ScipyOptimizer, self)._setup()
  File "/usr/local/lib/python2.7/site-packages/openmdao/core/driver.py", line 115, in _setup
    (item_name, name, oname))
RuntimeError: Parameter 'childWeight.x' is a 'pass_by_obj' variable and can't be used with a gradient based driver of type 'BFGS'.

Answer 1

问题出在这一行

root.add('childWeight', IndepVarComp('x',240))

您已经创建了一个整型变量。试试这个:

root.add('childWeight', IndepVarComp('x',240.))

如果您想使用有限差分，您还需要:

top.root.fd_options['force_fd'] = True