Issue2099

doc/changes/2111.feature

@@ -0,0 +1 @@
+Added __repr__ to QobjEvo

qutip/core/cy/qobjevo.pyx

@@ -241,6 +241,13 @@ cdef class QobjEvo:
         if compress:
             self.compress()
 
+    def __repr__(self):
+        cls = self.__class__.__name__
+        repr_str = f'{cls}: dims = {self.dims}, shape = {self.shape}, '
+        repr_str += f'type = {self.type}, superrep = {self.superrep}, '
+        repr_str += f'isconstant = {self.isconstant}, num_elements = {self.num_elements}'
+        return repr_str
+
     def _read_element(self, op, copy, tlist, args, order, function_style, 
                       boundary_conditions):
         """ Read a Q_object item and return an element for that item. """
@@ -456,13 +463,13 @@ cdef class QobjEvo:
         if isinstance(other, QobjEvo):
             if other.dims != self.dims:
                 raise TypeError("incompatible dimensions" +
-                                 str(self.dims) + ", " + str(other.dims))
+                                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:
                 raise TypeError("incompatible dimensions" +
-                                 str(self.dims) + ", " + str(other.dims))
+                                str(self.dims) + ", " + str(other.dims))
             self.elements.append(_ConstantElement(other))
         elif (
             isinstance(other, numbers.Number) and
@@ -992,9 +999,9 @@ cdef class QobjEvo:
                              ", " + 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
-                   )
+                    )
 
     cpdef Data matmul_data(QobjEvo self, object t, Data state, Data out=None):
         """Compute ``out += self(t) @ state``"""

qutip/tests/core/test_qobjevo.py

@@ -2,7 +2,8 @@
 
 import pytest
 from qutip import (Qobj, QobjEvo, coefficient, qeye, sigmax, sigmaz,
-                   rand_stochastic, rand_herm, rand_ket, liouvillian)
+                   rand_stochastic, rand_herm, rand_ket, liouvillian,
+                   basis, spre, spost, to_choi)
 import numpy as np
 from numpy.testing import assert_allclose
 
@@ -132,6 +133,45 @@ def test_call(pseudo_qevo, coeff_type):
     _assert_qobjevo_equivalent(pseudo_qevo, qevo)
 
 
+# Test the QobjEvo.__repr__()
+def test_QobjEvo_repr():
+    # case_n: cases with Objects of QobjEvo with unique __repr__
+    # expected_repr_n: are the Expected result from the __repr__
+
+    case_1 = repr(QobjEvo([qeye(3), lambda t: t]))
+    expected_repr_1 = 'QobjEvo: dims = [[3], [3]], shape = (3, 3), '
+    expected_repr_1 += 'type = oper, superrep = None, '
+    expected_repr_1 += 'isconstant = False, num_elements = 1'
+    assert case_1 == expected_repr_1
+
+    case_2 = repr(QobjEvo(qeye(2)))
+    expected_repr_2 = 'QobjEvo: dims = [[2], [2]], shape = (2, 2), '
+    expected_repr_2 += 'type = oper, superrep = None, '
+    expected_repr_2 += 'isconstant = True, num_elements = 1'
+    assert case_2 == expected_repr_2
+
+    case_3 = repr(QobjEvo(basis(5, 2)))
+    expected_repr_3 = 'QobjEvo: dims = [[5], [1]], shape = (5, 1), '
+    expected_repr_3 += 'type = ket, superrep = None, '
+    expected_repr_3 += 'isconstant = True, num_elements = 1'
+    assert case_3 == expected_repr_3
+
+    X = sigmax()
+    S = spre(X) * spost(X.dag())
+    case_4 = repr(QobjEvo(to_choi(S)))
+    expected_repr_4 = 'QobjEvo: dims = [[[2], [2]], [[2], [2]]], '
+    expected_repr_4 += 'shape = (4, 4), type = super, superrep = choi, '
+    expected_repr_4 += 'isconstant = True, num_elements = 1'
+    assert case_4 == expected_repr_4
+
+    case_5 = repr(QobjEvo([[qeye(4), lambda t: t],
+                           [qeye(4), lambda t: t]], compress=False))
+    expected_repr_5 = 'QobjEvo: dims = [[4], [4]], shape = (4, 4), '
+    expected_repr_5 += 'type = oper, superrep = None, '
+    expected_repr_5 += 'isconstant = False, num_elements = 2'
+    assert case_5 == expected_repr_5
+
+
 @pytest.mark.parametrize('coeff_type',
                          ['func_coeff', 'string', 'array', 'logarray'])
 def test_product_coeff(pseudo_qevo, coeff_type):