`GensetModule.sample_action()` raises `TypeError` when called via `Microgrid.sample_action(strict_bound=True)`

[petermllrr]

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• python version: 3.12.3
• python-microgrid version: 1.4.1

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Bug Report

• Bug Description:

Calling microgrid.sample_action(strict_bound=True) on any microgrid that contains a GensetModule raises a TypeError at runtime.

• Steps to reproduce:

This can be reproduced with the example in the README:

import numpy as np
from pymgrid import Microgrid
from pymgrid.modules import GensetModule, BatteryModule, LoadModule, RenewableModule

genset = GensetModule(running_min_production=10,
                      running_max_production=50,
                      genset_cost=0.5)

battery = BatteryModule(min_capacity=0,
                        max_capacity=100,
                        max_charge=50,
                        max_discharge=50,
                        efficiency=1.0,
                        init_soc=0.5)

renewable = RenewableModule(time_series=50*np.random.rand(100))

load = LoadModule(time_series=60*np.random.rand(100))

microgrid = Microgrid([genset, battery, ("pv", renewable), load])

for j in range(10):
    action = microgrid.sample_action(strict_bound=True)
    microgrid.step(action)

This throws a TypeError:

Traceback (most recent call last):
  File "reproduce_bug.py", line 30, in <module>
    action = microgrid.sample_action(strict_bound=True)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/pymgrid/microgrid/microgrid.py", line 381, in sample_action
    return {module_name: [module.sample_action(strict_bound=strict_bound) for module in module_list]
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/pymgrid/modules/genset_module.py", line 364, in sample_action
    return np.array([np.random.rand(), super().sample_action(strict_bound=strict_bound)])
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/pymgrid/modules/base/base_module.py", line 357, in sample_action
    max_bound = self._action_space.normalize(self.max_production)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/pymgrid/utils/space/space.py", line 330, in normalize
    self._shape_check(val, 'normalize')
  File "src/pymgrid/utils/space/space.py", line 170, in _shape_check
    raise TypeError(f'Unable to {func} scalar value, expected array-like of shape {len(low)}')
TypeError: Unable to normalize scalar value, expected array-like of shape 2

• Expected behavior:

Microgrid executes sample_action for the Genset module with a value between 10 and 50 and on_off 0 or 1.

• Other context:

GensetModule has a 2-dimensional action space — [on_off_flag, power_setpoint] — but its sample_action delegates the power component to super().sample_action() (i.e. BaseModule), which expects a scalar action space. When BaseModule tries to normalize self.max_production (a scalar) against an action space of shape (2,), the shape check fails.