[Stable] Add scikit-learn dependency and add CI job without optional dependencies (#436)

.travis.yml

@@ -101,6 +101,12 @@ matrix:
         - MPLBACKEND=ps
         - PYTHON_VERSION=3.8.1
         - TOXENV=py38
+    - python: "3.8"
+      name: "Python 3.8 tests without optional dependencies"
+      stage: all_python
+      env: TOXENV=no-opt
+      stage: all_python
+      script: tox
     - if: tag IS present
       python: "3.6"
       env:

releasenotes/notes/missing-dependency-e7c99c7751bcd162.yaml

@@ -0,0 +1,10 @@
+---
+upgrade:
+  - |
+    A new requirement `scikit-learn <https://scikit-learn.org/stable/>`__ has
+    been added to the requirements list. This dependency was added in the 0.3.0
+    release but wasn't properly exposed as a dependency in that release. This
+    would lead to an ``ImportError`` if the
+    :mod:`qiskit.ignis.measurement.discriminator.iq_discriminators` module was
+    imported. This is now correctly listed as a dependency so that
+    ``scikit-learn`` will be installed with qiskit-ignis.

setup.py

@@ -23,6 +23,7 @@
     "qiskit-terra>=0.13.0",
     "scipy>=0.19,!=0.19.1",
     "setuptools>=40.1.0",
+    "scikit-learn>=0.17",
 ]
 
 

test/tomography/test_process_tomography.py

@@ -24,32 +24,40 @@
 from qiskit.quantum_info import Choi
 
 import qiskit.ignis.verification.tomography as tomo
+from qiskit.ignis.verification.tomography.fitters import cvx_fit
 
 
-def run_circuit_and_tomography(circuit, qubits):
+def run_circuit_and_tomography(circuit, qubits, method):
     choi_ideal = Choi(circuit).data
     qst = tomo.process_tomography_circuits(circuit, qubits)
     job = qiskit.execute(qst, Aer.get_backend('qasm_simulator'),
                          shots=5000)
     tomo_fit = tomo.ProcessTomographyFitter(job.result(), qst)
-    choi_cvx = tomo_fit.fit(method='cvx').data
-    choi_mle = tomo_fit.fit(method='lstsq').data
-    return (choi_cvx, choi_mle, choi_ideal)
+    choi = tomo_fit.fit(method=method).data
+    return (choi, choi_ideal)
 
 
 class TestProcessTomography(unittest.TestCase):
+    def setUp(self):
+        super().setUp()
+        self.method = 'lstsq'
 
     def test_bell_2_qubits(self):
         q2 = QuantumRegister(2)
         bell = QuantumCircuit(q2)
         bell.h(q2[0])
         bell.cx(q2[0], q2[1])
 
-        choi_cvx, choi_mle, choi_ideal = run_circuit_and_tomography(bell, q2)
-        F_bell_cvx = state_fidelity(choi_ideal/4, choi_cvx/4, validate=False)
-        self.assertAlmostEqual(F_bell_cvx, 1, places=1)
-        F_bell_mle = state_fidelity(choi_ideal/4, choi_mle/4, validate=False)
-        self.assertAlmostEqual(F_bell_mle, 1, places=1)
+        choi, choi_ideal = run_circuit_and_tomography(bell, q2, self.method)
+        F_bell = state_fidelity(choi_ideal/4, choi/4, validate=False)
+        self.assertAlmostEqual(F_bell, 1, places=1)
+
+
+@unittest.skipUnless(cvx_fit._HAS_CVX, 'cvxpy is required for this test')
+class TestProcessTomographyCVX(TestProcessTomography):
+    def setUp(self):
+        super().setUp()
+        self.method = 'cvx'
 
 
 if __name__ == '__main__':

test/tomography/test_state_tomography.py

@@ -26,19 +26,18 @@
 import qiskit.ignis.verification.tomography.fitters.cvx_fit as cvx_fit
 
 
-def run_circuit_and_tomography(circuit, qubits):
+def run_circuit_and_tomography(circuit, qubits, method='lstsq'):
     psi = Statevector.from_instruction(circuit)
     qst = tomo.state_tomography_circuits(circuit, qubits)
     job = qiskit.execute(qst, Aer.get_backend('qasm_simulator'),
                          shots=5000)
     tomo_fit = tomo.StateTomographyFitter(job.result(), qst)
-    rho_cvx = tomo_fit.fit(method='cvx')
-    rho_mle = tomo_fit.fit(method='lstsq')
-    return (rho_cvx, rho_mle, psi)
+    rho = tomo_fit.fit(method=method)
+    return (rho, psi)
 
 
+@unittest.skipUnless(cvx_fit._HAS_CVX, 'cvxpy is required to run this test')
 class TestFitter(unittest.TestCase):
-
     def test_trace_constraint(self):
         p = numpy.array([1/2, 1/2, 1/2, 1/2, 1/2, 1/2])
 
@@ -58,29 +57,28 @@ def test_trace_constraint(self):
 
 
 class TestStateTomography(unittest.TestCase):
+    def setUp(self):
+        super().setUp()
+        self.method = 'lstsq'
 
     def test_bell_2_qubits(self):
         q2 = QuantumRegister(2)
         bell = QuantumCircuit(q2)
         bell.h(q2[0])
         bell.cx(q2[0], q2[1])
 
-        rho_cvx, rho_mle, psi = run_circuit_and_tomography(bell, q2)
-        F_bell_cvx = state_fidelity(psi, rho_cvx, validate=False)
-        self.assertAlmostEqual(F_bell_cvx, 1, places=1)
-        F_bell_mle = state_fidelity(psi, rho_mle, validate=False)
-        self.assertAlmostEqual(F_bell_mle, 1, places=1)
+        rho, psi = run_circuit_and_tomography(bell, q2, self.method)
+        F_bell = state_fidelity(psi, rho, validate=False)
+        self.assertAlmostEqual(F_bell, 1, places=1)
 
     def test_bell_2_qubits_no_register(self):
         bell = QuantumCircuit(2)
         bell.h(0)
         bell.cx(0, 1)
 
-        rho_cvx, rho_mle, psi = run_circuit_and_tomography(bell, (0, 1))
-        F_bell_cvx = state_fidelity(psi, rho_cvx, validate=False)
-        self.assertAlmostEqual(F_bell_cvx, 1, places=1)
-        F_bell_mle = state_fidelity(psi, rho_mle, validate=False)
-        self.assertAlmostEqual(F_bell_mle, 1, places=1)
+        rho, psi = run_circuit_and_tomography(bell, (0, 1), self.method)
+        F_bell = state_fidelity(psi, rho, validate=False)
+        self.assertAlmostEqual(F_bell, 1, places=1)
 
     def test_different_qubit_sets(self):
         circuit = QuantumCircuit(5)
@@ -92,12 +90,10 @@ def test_different_qubit_sets(self):
         circuit.cx(1, 3)
 
         for qubit_pair in [(0, 1), (2, 3), (1, 4), (0, 3)]:
-            rho_cvx, rho_mle, psi = run_circuit_and_tomography(circuit, qubit_pair)
+            rho, psi = run_circuit_and_tomography(circuit, qubit_pair, self.method)
             psi = partial_trace(psi, [x for x in range(5) if x not in qubit_pair])
-            F_cvx = state_fidelity(psi, rho_cvx, validate=False)
-            self.assertAlmostEqual(F_cvx, 1, places=1)
-            F_mle = state_fidelity(psi, rho_mle, validate=False)
-            self.assertAlmostEqual(F_mle, 1, places=1)
+            F = state_fidelity(psi, rho, validate=False)
+            self.assertAlmostEqual(F, 1, places=1)
 
     def test_bell_3_qubits(self):
         q3 = QuantumRegister(3)
@@ -106,22 +102,18 @@ def test_bell_3_qubits(self):
         bell.cx(q3[0], q3[1])
         bell.cx(q3[1], q3[2])
 
-        rho_cvx, rho_mle, psi = run_circuit_and_tomography(bell, q3)
-        F_bell_cvx = state_fidelity(psi, rho_cvx, validate=False)
-        self.assertAlmostEqual(F_bell_cvx, 1, places=1)
-        F_bell_mle = state_fidelity(psi, rho_mle, validate=False)
-        self.assertAlmostEqual(F_bell_mle, 1, places=1)
+        rho, psi = run_circuit_and_tomography(bell, q3, self.method)
+        F_bell = state_fidelity(psi, rho, validate=False)
+        self.assertAlmostEqual(F_bell, 1, places=1)
 
     def test_complex_1_qubit_circuit(self):
         q = QuantumRegister(1)
         circ = QuantumCircuit(q)
         circ.u3(1, 1, 1, q[0])
 
-        rho_cvx, rho_mle, psi = run_circuit_and_tomography(circ, q)
-        F_bell_cvx = state_fidelity(psi, rho_cvx, validate=False)
-        self.assertAlmostEqual(F_bell_cvx, 1, places=1)
-        F_bell_mle = state_fidelity(psi, rho_mle, validate=False)
-        self.assertAlmostEqual(F_bell_mle, 1, places=1)
+        rho, psi = run_circuit_and_tomography(circ, q, self.method)
+        F_bell = state_fidelity(psi, rho, validate=False)
+        self.assertAlmostEqual(F_bell, 1, places=1)
 
     def test_complex_3_qubit_circuit(self):
         def rand_angles():
@@ -133,11 +125,16 @@ def rand_angles():
         for j in range(3):
             circ.u3(*rand_angles(), q[j])
 
-        rho_cvx, rho_mle, psi = run_circuit_and_tomography(circ, q)
-        F_bell_cvx = state_fidelity(psi, rho_cvx, validate=False)
-        self.assertAlmostEqual(F_bell_cvx, 1, places=1)
-        F_bell_mle = state_fidelity(psi, rho_mle, validate=False)
-        self.assertAlmostEqual(F_bell_mle, 1, places=1)
+        rho, psi = run_circuit_and_tomography(circ, q, self.method)
+        F_bell = state_fidelity(psi, rho, validate=False)
+        self.assertAlmostEqual(F_bell, 1, places=1)
+
+
+@unittest.skipUnless(cvx_fit._HAS_CVX, 'cvxpy is required  to run this test')
+class TestStateTomographyCVX(TestStateTomography):
+    def setUp(self):
+        super().setUp()
+        self.method = 'cvx'
 
 
 if __name__ == '__main__':

tox.ini

@@ -20,6 +20,15 @@ commands =
     pip check
     stestr run {posargs}
 
+[testenv:no-opt]
+deps =
+    qiskit-aer
+    ddt>=1.2.0,!=1.4.0
+    stestr>=2.5.0
+commands =
+    pip check
+    stestr run {posargs}
+
 [testenv:lint]
 basepython = python3
 deps =