Class MPBArray

python/solver.py:31–71

class MPBArray(np.ndarray):
    def __new__(cls, input_array, lattice, kpoint=None, bloch_phase=False):
        # Input array is an already formed ndarray instance
        # We first cast to be our class type
        obj = np.asarray(input_array).view(cls)
        # add the new properties to the created instance
        obj.lattice = lattice
        obj.kpoint = kpoint
        obj.bloch_phase = bloch_phase
        # Finally, we must return the newly created object:
        return obj

    def __array_finalize__(self, obj):
        # ``self`` is a new object resulting from
        # ndarray.__new__(MPBArray, ...), therefore it only has
        # attributes that the ndarray.__new__ constructor gave it -
        # i.e. those of a standard ndarray.

        # We could have got to the ndarray.__new__ call in 3 ways:
        # From an explicit constructor - e.g. MPBArray(lattice):
        #    obj is None
        #    (we're in the middle of the MPBArray.__new__
        #    constructor, and self.lattice will be set when we return to
        #    MPBArray.__new__)
        if obj is None:
            return

        # From view casting - e.g arr.view(MPBArray):
        #    obj is arr
        #    (type(obj) can be MPBArray)
        # From new-from-template - e.g mpbarr[:3]
        #    type(obj) is MPBArray
        #
        # Note that it is here, rather than in the __new__ method,
        # that we set the default value for 'lattice', because this
        # method sees all creation of default objects - with the
        # MPBArray.__new__ constructor, but also with
        # arr.view(MPBArray).
        self.lattice = getattr(obj, "lattice", None)
        self.kpoint = getattr(obj, "kpoint", None)
        self.bloch_phase = getattr(obj, "bloch_phase", False)


class ModeSolver: