Adding QUADCOIL integration to DESC as an objective

desc/coils.py

@@ -949,6 +949,33 @@
             name=name,
         )
 
+    @classmethod
+    def from_simsopt(cls, coil_simsopt, name=""):
+        """Load a simsopt coil as a FourierXYZCoil.
+
+        Parameters
+        ----------
+        coil_simsopt : simsopt.field.Coil
+            A simsopt coil
+        name : str
+            Name for this coil.
+
+        Returns
+        -------
+        coil : FourierXYZCoil
+            A FourierXYZCoil.
+        """
+        current = coil_simsopt.current.get_value()
+        curve = FourierXYZCurve.from_simsopt(coil_simsopt.curve)
+        return cls(
+            current=current,
+            X_n=curve.X_n,
+            Y_n=curve.Y_n,
+            Z_n=curve.Z_n,
+            modes=curve.X_basis.modes[:, 2],
+            name=name,
+        )
+
 
 class FourierPlanarCoil(_Coil, FourierPlanarCurve):
     """Coil that lies in a plane.

desc/geometry/curve.py

@@ -631,6 +631,47 @@
             X_n=X_n, Y_n=Y_n, Z_n=Z_n, modes=basis.modes[:, 2], name=name
         )
 
+    @classmethod
+    def from_simsopt(cls, curve_simsopt, name=""):
+        """Load a simsopt CurveXYZFourier as a FourierXYZCurve.
+
+        Parameters
+        ----------
+        coil_simsopt : simsopt.geo.CurveXYZFourier
+            A simsopt curve
+        name : str
+            Name for this curve.
+
+        Returns
+        -------
+        coil : FourierXYZCurve
+            A FourierXYZCurve.
+        """
+        try:
+            from simsopt.geo import CurveXYZFourier
+        except ModuleNotFoundError:
+            raise ModuleNotFoundError("from_simsopt method requires simsopt package.")
+        if not isinstance(curve_simsopt, CurveXYZFourier):
+            raise AttributeError("The imput curve must be a Simsopt CurveXYZFourier")
+        dofs = curve_simsopt.get_dofs()
+        order = curve_simsopt.order
+        # [xc0, xs1, xc1, ....]
+        x = dofs[: 2 * order + 1]
+        y = dofs[2 * order + 1 : 4 * order + 2]
+        z = dofs[4 * order + 2 :]
+
+        def convert_x(x):
+            xc = x[::2]
+            xs = x[1:][::2]
+            xn = np.concatenate((np.flip(xs), xc))
+            return xn
+
+        xn = convert_x(x)
+        yn = convert_x(y)
+        zn = convert_x(z)
+        modes = np.arange(-order, order + 1)
+        return cls(xn, yn, zn, modes=modes, name=name)
+
     def _get_ess_scale(self, alpha=1.2, order=np.inf, min_value=1e-7):
         """Create x_scale using exponential spectral scaling.
 

desc/io/optimizable_io.py

@@ -92,7 +92,7 @@ def _make_hashable(x):
 
 def _unmake_hashable(x):
     # turn tuple of ints and shape to ndarray
-    if isinstance(x, tuple) and x[0] == "ndarray":
+    if isinstance(x, tuple) and len(x) and x[0] == "ndarray":
         return np.array(x[2]).reshape(x[1])
     if isinstance(x, list):
         return [_unmake_hashable(y) for y in x]

desc/objectives/__init__.py

@@ -56,6 +56,7 @@
 )
 from ._power_balance import FusionPower, HeatingPowerISS04
 from ._profiles import Pressure, RotationalTransform, Shear, ToroidalCurrent
+from ._quadcoil import QuadcoilProxy
 from ._stability import BallooningStability, MagneticWell, MercierStability
 from .getters import (
     get_equilibrium_objective,