Code style, Python type hinting

[samlyme]

There are many examples of poorly written python code, leading to type hinting errors, even if the code runs.

For example, on line 279 of gym_pybullet_drones/control/DSLPIDControl.py, we see:

        DIM = len(np.array(thrust))
        pwm = np.clip((np.sqrt(np.array(thrust)/(self.KF*(4/DIM)))-self.PWM2RPM_CONST)/self.PWM2RPM_SCALE, self.MIN_PWM, self.MAX_PWM)
        if DIM in [1, 4]:
            return np.repeat(pwm, 4/DIM)
        elif DIM==2:
            return np.hstack([pwm, np.flip(pwm)])
        else:
            print("[ERROR] in DSLPIDControl._one23DInterface()")
            exit()

Leading to the type error:

No overloads for "repeat" match the provided arguments
Argument of type "float" cannot be assigned to parameter "repeats" of type "_ArrayLikeInt_co" in function "repeat"
  Type "float" is not assignable to type "_ArrayLikeInt_co"
    "float" is incompatible with protocol "_SupportsArray[dtype[numpy.bool[builtins.bool] | integer[Any]]]"
      "__array__" is not present
    "float" is incompatible with protocol "_NestedSequence[_SupportsArray[dtype[numpy.bool[builtins.bool] | integer[Any]]]]"
      "__len__" is not present
      "__getitem__" is not present
      "__contains__" is not present
      "__iter__" is not present
  ...

This is because np.repeat expects an integer value for the Dimensions. Thus,

        DIM = len(np.array(thrust))
        pwm = np.clip((np.sqrt(np.array(thrust)/(self.KF*(4/DIM)))-self.PWM2RPM_CONST)/self.PWM2RPM_SCALE, self.MIN_PWM, self.MAX_PWM)
        if DIM in [1, 4]:
            return np.repeat(pwm, 4//DIM)
        elif DIM==2:
            return np.hstack([pwm, np.flip(pwm)])
        else:
            print("[ERROR] in DSLPIDControl._one23DInterface()")
            exit()

Fixes the type issue.

I love this project and would love to contribute! I am working on a just generally cleaning the code.

[JacopoPan]

Please feel free and encouraged to contribute even purely stylistic fixes via PR 🙏