Dimensions class

doc/apidoc/functions.rst

@@ -11,14 +11,21 @@ Quantum States
 --------------
 
 .. automodule:: qutip.core.states
-    :members: basis, bell_state, bra, coherent, coherent_dm, enr_state_dictionaries, enr_thermal_dm, enr_fock, fock, fock_dm, ghz_state, maximally_mixed_dm, ket, ket2dm, phase_basis, projection, qutrit_basis, singlet_state, spin_state, spin_coherent, state_number_enumerate, state_number_index, state_index_number, state_number_qobj, thermal_dm, triplet_states, w_state, zero_ket
+    :members: basis, bell_state, bra, coherent, coherent_dm, fock, fock_dm, ghz_state, maximally_mixed_dm, ket, ket2dm, phase_basis, projection, qutrit_basis, singlet_state, spin_state, spin_coherent, state_number_enumerate, state_number_index, state_index_number, state_number_qobj, thermal_dm, triplet_states, w_state, zero_ket
 
 
 Quantum Operators
 -----------------
 
 .. automodule:: qutip.core.operators
-    :members: charge, commutator, create, destroy, displace, enr_destroy, enr_identity, fcreate, fdestroy, jmat, num, qeye, identity, momentum, phase, position, qdiags, qutrit_ops, qzero, sigmam, sigmap, sigmax, sigmay, sigmaz, spin_Jx, spin_Jy, spin_Jz, spin_Jm, spin_Jp, squeeze, squeezing, tunneling
+    :members: charge, commutator, create, destroy, displace, fcreate, fdestroy, jmat, num, qeye, identity, momentum, phase, position, qdiags, qutrit_ops, qzero, sigmam, sigmap, sigmax, sigmay, sigmaz, spin_Jx, spin_Jy, spin_Jz, spin_Jm, spin_Jp, squeeze, squeezing, tunneling
+
+
+Energy Restricted Operators
+---------------------------
+
+.. automodule:: qutip.core.energy_restricted
+    :members: enr_state_dictionaries, enr_thermal_dm, enr_fock, enr_destroy, enr_identity
 
 
 .. _functions-rand:
@@ -54,7 +61,7 @@ Operators and Superoperator Dimensions
 --------------------------------------
 
 .. automodule:: qutip.core.dimensions
-    :members: is_scalar, is_vector, is_vectorized_oper, type_from_dims, flatten, deep_remove, unflatten, collapse_dims_oper, collapse_dims_super, enumerate_flat, deep_map, dims_to_tensor_perm, dims_to_tensor_shape, dims_idxs_to_tensor_idxs
+    :members: flatten, deep_remove, unflatten, collapse_dims_oper, collapse_dims_super, enumerate_flat, deep_map, dims_to_tensor_perm, dims_to_tensor_shape, dims_idxs_to_tensor_idxs
 
 
 Functions acting on states and operators

doc/changes/1996.feature

@@ -0,0 +1 @@
+Create a Dimension class

qutip/core/__init__.py

@@ -11,6 +11,7 @@
 from .superop_reps import *
 from .subsystem_apply import *
 from .blochredfield import *
+from .energy_restricted import *
 from . import gates
 
 del cy  # File in cy are not public facing

qutip/core/_brtensor.pyx

@@ -266,8 +266,7 @@ cdef class _BlochRedfieldElement(_BaseElement):
         raise ValueError('Invalid tensortype')
 
     cpdef object qobj(self, t):
-        return Qobj(self.data(t), dims=self.dims, type="super",
-                    copy=False, superrep="super")
+        return Qobj(self.data(t), dims=self.dims, copy=False, superrep="super")
 
     cpdef object coeff(self, t):
         return 1.

qutip/core/cy/qobjevo.pxd

@@ -6,10 +6,8 @@ from qutip.core.data.base cimport idxint
 cdef class QobjEvo:
     cdef:
         list elements
-        readonly list dims
+        readonly object _dims
         readonly (idxint, idxint) shape
-        readonly str type
-        readonly str superrep
         int _issuper
         int _isoper
 

qutip/core/cy/qobjevo.pyx

@@ -9,17 +9,16 @@ from functools import partial
 import qutip
 from .. import Qobj
 from .. import data as _data
+from ..dimensions import Dimensions
 from ..coefficient import coefficient, CompilationOptions
 from ._element import *
-from ..dimensions import type_from_dims
 from qutip.settings import settings
 
 from qutip.core.cy._element cimport _BaseElement
 from qutip.core.data cimport Dense, Data, dense
 from qutip.core.data.expect cimport *
 from qutip.core.data.reshape cimport (column_stack_dense, column_unstack_dense)
 from qutip.core.cy.coefficient cimport Coefficient
-from qutip.core.qobj import _MATMUL_TYPE_LOOKUP
 from libc.math cimport fabs
 
 __all__ = ['QobjEvo']
@@ -135,7 +134,6 @@ cdef class QobjEvo:
 
         QobjEvo(f, args={'w': 1j})
 
-
     For list based :obj:`~QobjEvo`, the list must consist of :obj`~Qobj` or
     ``[Qobj, Coefficient]`` pairs:
 
@@ -192,11 +190,8 @@ cdef class QobjEvo:
                  order=3, copy=True, compress=True,
                  function_style=None, boundary_conditions=None):
         if isinstance(Q_object, QobjEvo):
-            self.dims = Q_object.dims.copy()
+            self._dims = Q_object._dims
             self.shape = Q_object.shape
-            self.type = Q_object.type
-            self._issuper = (<QobjEvo> Q_object)._issuper
-            self._isoper = (<QobjEvo> Q_object)._isoper
             self.elements = (<QobjEvo> Q_object).elements.copy()
             if args:
                 self.arguments(args)
@@ -205,10 +200,8 @@ cdef class QobjEvo:
             return
 
         self.elements = []
-        self.dims = None
+        self._dims = None
         self.shape = (0, 0)
-        self._issuper = -1
-        self._isoper = -1
         args = args or {}
 
         if (
@@ -280,40 +273,25 @@ cdef class QobjEvo:
                 " received: {!r}".format(op)
             )
 
-        if self.dims is None:
-            self.dims = qobj.dims
+        if self._dims is None:
+            self._dims = qobj._dims
             self.shape = qobj.shape
-            self.type = qobj.type
-            self.superrep = qobj.superrep
-        elif self.dims != qobj.dims or self.shape != qobj.shape:
+        elif self._dims != qobj._dims:
             raise ValueError(
                 f"QobjEvo term {op!r} has dims {qobj.dims!r} and shape"
                 f" {qobj.shape!r} but previous terms had dims {self.dims!r}"
                 f" and shape {self.shape!r}."
             )
-        elif self.type != qobj.type:
-            raise ValueError(
-                f"QobjEvo term {op!r} has type {qobj.type!r} but "
-                f"previous terms had type {self.type!r}."
-            )
-        elif self.superrep != qobj.superrep:
-            raise ValueError(
-                f"QobjEvo term {op!r} has superrep {qobj.superrep!r} but "
-                f"previous terms had superrep {self.superrep!r}."
-            )
 
         return out
 
     @classmethod
-    def _restore(cls, elements, dims, shape, type, superrep, flags):
+    def _restore(cls, elements, dims, shape):
         """Recreate a QobjEvo without using __init__. """
         cdef QobjEvo out = cls.__new__(cls)
         out.elements = elements
-        out.dims = dims
+        out._dims = dims
         out.shape = shape
-        out.type = type
-        out.superrep = superrep
-        out._issuper, out._isoper = flags
         return out
 
     def _getstate(self):
@@ -324,11 +302,8 @@ cdef class QobjEvo:
         # etc., so we create our own.
         return {
             "elements": self.elements,
-            "dims": self.dims,
+            "dims": self._dims,
             "shape": self.shape,
-            "type": self.type,
-            "superrep": self.superrep,
-            "flags": (self._issuper, self._isoper,)
         }
 
     def __call__(self, double t, dict _args=None, **kwargs):
@@ -379,8 +354,7 @@ cdef class QobjEvo:
             out = _data.add(out, obj.data, coeff)
 
         return Qobj(
-            out, dims=self.dims, copy=False, isherm=isherm or None,
-            type=self.type, superrep=self.superrep
+            out, dims=self._dims, copy=False, isherm=isherm or None,
         )
 
     cpdef Data _call(QobjEvo self, double t):
@@ -461,19 +435,19 @@ cdef class QobjEvo:
     def __iadd__(QobjEvo self, other):
         cdef _BaseElement element
         if isinstance(other, QobjEvo):
-            if other.dims != self.dims:
+            if other._dims != self._dims:
                 raise TypeError("incompatible dimensions" +
                                 str(self.dims) + ", " + str(other.dims))
             for element in (<QobjEvo> other).elements:
                 self.elements.append(element)
         elif isinstance(other, Qobj):
-            if other.dims != self.dims:
+            if other._dims != self._dims:
                 raise TypeError("incompatible dimensions" +
                                 str(self.dims) + ", " + str(other.dims))
             self.elements.append(_ConstantElement(other))
         elif (
             isinstance(other, numbers.Number) and
-            self.dims[0] == self.dims[1]
+            self._dims[0] == self._dims[1]
         ):
             self.elements.append(_ConstantElement(other * qutip.qeye_like(self)))
         else:
@@ -508,53 +482,31 @@ cdef class QobjEvo:
         if isinstance(left, QobjEvo):
             return left.copy().__imatmul__(right)
         elif isinstance(left, Qobj):
-            if left.dims[1] != (<QobjEvo> right).dims[0]:
+            if left._dims[1] != (<QobjEvo> right)._dims[0]:
                 raise TypeError("incompatible dimensions" +
                                  str(left.dims[1]) + ", " +
                                  str((<QobjEvo> right).dims[0]))
-
-            type_ =_MATMUL_TYPE_LOOKUP.get((left.type, right.type))
-            if type_ is None:
-                raise TypeError(
-                    "incompatible matmul types "
-                    + repr(left.type) + " and " + repr(right.type)
-                )
-
             res = right.copy()
-            res.dims = [left.dims[0], right.dims[1]]
+            res._dims = Dimensions(left._dims[0], right._dims[1])
             res.shape = (left.shape[0], right.shape[1])
-            res.type = type_
             left = _ConstantElement(left)
             res.elements = [left @ element for element in res.elements]
-            res._issuper = -1
-            res._isoper = -1
             return res
         else:
             return NotImplemented
 
     def __rmatmul__(QobjEvo self, other):
         cdef QobjEvo res
         if isinstance(other, Qobj):
-            if other.dims[1] != self.dims[0]:
+            if other._dims[1] != self._dims[0]:
                 raise TypeError("incompatible dimensions" +
                                  str(other.dims[1]) + ", " +
                                  str(self.dims[0]))
-
-            type_ =_MATMUL_TYPE_LOOKUP.get((other.type, self.type))
-            if type_ is None:
-                raise TypeError(
-                    "incompatible matmul types "
-                    + repr(other.type) + " and " + repr(self.type)
-                )
-
             res = self.copy()
-            res.dims = [other.dims[0], res.dims[1]]
+            res._dims = Dimensions([other._dims[0], res._dims[1]])
             res.shape = (other.shape[0], res.shape[1])
-            res.type = type_
             other = _ConstantElement(other)
             res.elements = [other @ element for element in res.elements]
-            res._issuper = -1
-            res._isoper = -1
             return res
         else:
             return NotImplemented
@@ -565,19 +517,8 @@ cdef class QobjEvo:
                 raise TypeError("incompatible dimensions" +
                                 str(self.dims[1]) + ", " +
                                 str(other.dims[0]))
-
-            type_ =_MATMUL_TYPE_LOOKUP.get((self.type, other.type))
-            if type_ is None:
-                raise TypeError(
-                    "incompatible matmul types "
-                    + repr(self.type) + " and " + repr(other.type)
-                )
-
-            self.dims = [self.dims[0], other.dims[1]]
+            self._dims = Dimensions([self.dims[0], other.dims[1]])
             self.shape = (self.shape[0], other.shape[1])
-            self.type = type_
-            self._issuper = -1
-            self._isoper = -1
             if isinstance(other, Qobj):
                 other = _ConstantElement(other)
                 self.elements = [element @ other for element in self.elements]
@@ -734,11 +675,8 @@ cdef class QobjEvo:
                 raise TypeError("The op_mapping function must return a Qobj")
         cdef QobjEvo res = self.copy()
         res.elements = [element.linear_map(op_mapping) for element in res.elements]
-        res.dims = res.elements[0].qobj(0).dims
+        res._dims = res.elements[0].qobj(0)._dims
         res.shape = res.elements[0].qobj(0).shape
-        res.type = res.elements[0].qobj(0).type
-        res._issuper = res.elements[0].qobj(0).issuper
-        res._isoper = res.elements[0].qobj(0).isoper
         if not _skip_check:
             if res(0) != out:
                 raise ValueError("The mapping is not linear")
@@ -855,19 +793,24 @@ cdef class QobjEvo:
     @property
     def isoper(self):
         """Indicates if the system represents an operator."""
-        # TODO: isoper should be part of dims
-        if self._isoper == -1:
-            self._isoper = type_from_dims(self.dims) == "oper"
-        return self._isoper
+        return self._dims.type == "oper"
 
     @property
     def issuper(self):
         """Indicates if the system represents a superoperator."""
-        # TODO: issuper should/will be part of dims
-        # remove self._issuper then
-        if self._issuper == -1:
-            self._issuper = type_from_dims(self.dims) == "super"
-        return self._issuper
+        return self._dims.issuper
+
+    @property
+    def dims(self):
+        return self._dims.as_list()
+
+    @property
+    def type(self):
+        return self._dims.type
+
+    @property
+    def superrep(self):
+        return self._dims.superrep
 
     ###########################################################################
     # operation methods                                                       #
@@ -905,8 +848,8 @@ cdef class QobjEvo:
             raise ValueError("Must be an operator or super operator to compute"
                              " an expectation value")
         if not (
-            (self.dims[1] == state.dims[0]) or
-            (self.issuper and self.dims[1] == state.dims)
+            (self._dims[1] == state._dims[0]) or
+            (self.issuper and self._dims[1] == state._dims)
         ):
             raise ValueError("incompatible dimensions " + str(self.dims) +
                              ", " + str(state.dims))
@@ -994,12 +937,12 @@ cdef class QobjEvo:
         if not isinstance(state, Qobj):
             raise TypeError("A Qobj state is expected")
 
-        if self.dims[1] != state.dims[0]:
+        if self._dims[1] != state._dims[0]:
             raise ValueError("incompatible dimensions " + str(self.dims[1]) +
                              ", " + str(state.dims[0]))
 
         return Qobj(self.matmul_data(t, state.data),
-                    dims=[self.dims[0], state.dims[1]],
+                    dims=[self._dims[0], state._dims[1]],
                     copy=False
                     )