From 1d3e7ca686b47adf14ce906a1694f8943a619f78 Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Sat, 26 Oct 2019 22:00:52 +1100
Subject: [PATCH 1/9] method to check third party packages; lazy-loading of
 qiskit

---
 qctrlopencontrols/exceptions/exceptions.py  | 76 +++++++++++++++++++++
 qctrlopencontrols/qiskit/__init__.py        |  3 +
 qctrlopencontrols/qiskit/quantum_circuit.py | 27 ++++++--
 qctrlopencontrols/utility/__init__.py       | 13 ++++
 qctrlopencontrols/utility/check_packages.py | 53 ++++++++++++++
 tests/test_qiskit_sequence.py               |  3 +-
 6 files changed, 167 insertions(+), 8 deletions(-)
 create mode 100644 qctrlopencontrols/utility/__init__.py
 create mode 100644 qctrlopencontrols/utility/check_packages.py

diff --git a/qctrlopencontrols/exceptions/exceptions.py b/qctrlopencontrols/exceptions/exceptions.py
index c68c6d98..72d8493e 100644
--- a/qctrlopencontrols/exceptions/exceptions.py
+++ b/qctrlopencontrols/exceptions/exceptions.py
@@ -57,3 +57,79 @@ def __init__(self, description, arguments, extras=None):
             for key in self.extras:
                 self.message += '\n' + str(key) + '=' + repr(self.extras[key])
         super(ArgumentsValueError, self).__init__(self.message)
+
+
+class PackageVersionMismatchError(QctrlError):
+    """Exception raised when the version of required third party packages found but is
+    below the minimum required.
+
+    Parameters
+    ----------
+    description : string
+        Description of the why the error is raised.
+    arguments : dict
+        Dictionary that contains the package name, required minimum version.
+    extras : dict, optional
+        Other variables, such as the version found in the system,
+        that may be relevant to the error. Defaults to None.
+    """
+
+    def __init__(self, description, arguments, extras=None):
+        self.description = description
+        self.arguments = arguments
+        self.extras = extras
+        self.message = self.description
+
+        for key in self.arguments:
+            self.message += '\n' + str(key) + '=' + repr(self.arguments[key])
+        if extras is not None:
+            for key in self.extras:
+                self.message += '\n' + str(key) + '=' + repr(self.extras[key])
+        super(PackageVersionMismatchError, self).__init__(self.message)
+
+
+class PackageNotFoundError(QctrlError):
+    """Exception raised when the required third party packages is not found.
+
+    Parameters
+    ----------
+    description : string
+        Description of the why the error is raised.
+    arguments : dict
+        Dictionary that contains the package name and the required minimum version.
+    extras : dict, optional
+        Other variables that may be relevant to the error. Defaults to None.
+    """
+
+    def __init__(self, description, arguments, extras=None):
+        self.description = description
+        self.arguments = arguments
+        self.extras = extras
+        self.message = self.description
+
+        for key in self.arguments:
+            self.message += '\n' + str(key) + '=' + repr(self.arguments[key])
+        if extras is not None:
+            for key in self.extras:
+                self.message += '\n' + str(key) + '=' + repr(self.extras[key])
+        super(PackageNotFoundError, self).__init__(self.message)
+
+
+class PackageImportError(QctrlError):
+    """Exception raised when a package cannot be imported.
+
+    Parameters
+    ----------
+    description : string
+        Description of the why the error is raised.
+    package_name : string, optional
+        The name of the package that could not be imported. Defaults to None.
+    """
+    def __init__(self, description, package_name=None):
+        self.description = description
+        self.package_name = package_name
+        self.message = self.description
+
+        if package_name:
+            self.message += '\n' + 'package' + '=' + repr(self.arguments[package_name])
+        super(PackageImportError, self).__init__(self.message)
diff --git a/qctrlopencontrols/qiskit/__init__.py b/qctrlopencontrols/qiskit/__init__.py
index a2b61496..46850731 100644
--- a/qctrlopencontrols/qiskit/__init__.py
+++ b/qctrlopencontrols/qiskit/__init__.py
@@ -11,3 +11,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
+# Minimum Qiskit version required
+qiskit_minimum_version = '0.10.0'
diff --git a/qctrlopencontrols/qiskit/quantum_circuit.py b/qctrlopencontrols/qiskit/quantum_circuit.py
index ca348cab..27354af7 100644
--- a/qctrlopencontrols/qiskit/quantum_circuit.py
+++ b/qctrlopencontrols/qiskit/quantum_circuit.py
@@ -20,13 +20,11 @@
 
 import numpy as np
 
-from qiskit import (
-    QuantumRegister, ClassicalRegister, QuantumCircuit)
-from qiskit.qasm import pi
-
-from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
-from ..exceptions.exceptions import ArgumentsValueError
 from ..globals import (FIX_DURATION_UNITARY, INSTANT_UNITARY)
+from ..qiskit import qiskit_minimum_version
+from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
+from ..exceptions.exceptions import ArgumentsValueError, PackageImportError
+from ..utility.check_packages import check_package
 
 
 def convert_dds_to_qiskit_quantum_circuit(
@@ -75,6 +73,12 @@ def convert_dds_to_qiskit_quantum_circuit(
     ------
     ArgumentsValueError
         If any of the input parameters are invalid
+    PackageNotFoundError
+        If Qiskit is not found
+    PackageVersionMismatchError
+        If the required minimum version of Qiskit is not found
+    PackageImportError
+        If Qiskit cannot be imported
 
     Notes
     -----
@@ -97,6 +101,17 @@ def convert_dds_to_qiskit_quantum_circuit(
     any offset.
     """
 
+    check_package('qiskit-terra', qiskit_minimum_version)
+
+    try:
+        from qiskit import (
+            QuantumRegister, ClassicalRegister, QuantumCircuit)
+        from qiskit.qasm import pi
+    except ImportError:
+        raise PackageImportError(
+            'Error while trying to import Qiskit.'
+        )
+
     if dynamic_decoupling_sequence is None:
         raise ArgumentsValueError('No dynamic decoupling sequence provided.',
                                   {'dynamic_decoupling_sequence': dynamic_decoupling_sequence})
diff --git a/qctrlopencontrols/utility/__init__.py b/qctrlopencontrols/utility/__init__.py
new file mode 100644
index 00000000..a2b61496
--- /dev/null
+++ b/qctrlopencontrols/utility/__init__.py
@@ -0,0 +1,13 @@
+# Copyright 2019 Q-CTRL Pty Ltd & Q-CTRL Inc
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
diff --git a/qctrlopencontrols/utility/check_packages.py b/qctrlopencontrols/utility/check_packages.py
new file mode 100644
index 00000000..09f91ce1
--- /dev/null
+++ b/qctrlopencontrols/utility/check_packages.py
@@ -0,0 +1,53 @@
+# Copyright 2019 Q-CTRL Pty Ltd & Q-CTRL Inc
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Module with helper methods to check for third party packages.
+"""
+
+import pkg_resources
+from pkg_resources import DistributionNotFound
+from packaging.version import parse
+
+
+from qctrlopencontrols.exceptions.exceptions import (
+    PackageVersionMismatchError,
+    PackageNotFoundError)
+
+
+def check_package(package_name, minimum_package_version):
+    """Checks if the specified package and its minimum version
+    exists.
+
+    Parameters
+    ---------
+    package_name: str
+        The name of the package
+    minimum_package_version: str
+        The minimum version of the package
+    """
+
+    try:
+        found_version = pkg_resources.get_distribution(package_name).version
+        if parse(found_version) < parse(minimum_package_version):
+            raise PackageVersionMismatchError(
+                'Minimum version of the {} package not found.'.format(package_name),
+                {'package name': package_name,
+                 'minimum package version': minimum_package_version},
+                extras={'version found': found_version})
+    except DistributionNotFound:
+        raise PackageNotFoundError(
+            'Package {} not found.'.format(package_name),
+            {'package name': package_name,
+             'minimum package version': minimum_package_version})
diff --git a/tests/test_qiskit_sequence.py b/tests/test_qiskit_sequence.py
index e58ca8f1..c11ecd0b 100644
--- a/tests/test_qiskit_sequence.py
+++ b/tests/test_qiskit_sequence.py
@@ -14,7 +14,7 @@
 
 """
 ===================================
-Tests converstion to Qiskit Circuit
+Tests conversion to Qiskit Circuit
 ===================================
 """
 
@@ -127,6 +127,5 @@ def test_identity_operation():
     _check_circuit_unitary(True, _multiplier, 'fixed duration unitary')
 
 
-
 if __name__ == '__main__':
     pass

From 16f737db2b62e310802b1649a5885235fa6e7c52 Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Sat, 26 Oct 2019 22:16:41 +1100
Subject: [PATCH 2/9] linted

---
 qctrlopencontrols/exceptions/exceptions.py  | 2 +-
 qctrlopencontrols/qiskit/__init__.py        | 8 +++++++-
 qctrlopencontrols/qiskit/quantum_circuit.py | 4 ++--
 qctrlopencontrols/utility/check_packages.py | 7 +++++++
 4 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/qctrlopencontrols/exceptions/exceptions.py b/qctrlopencontrols/exceptions/exceptions.py
index 72d8493e..dd075304 100644
--- a/qctrlopencontrols/exceptions/exceptions.py
+++ b/qctrlopencontrols/exceptions/exceptions.py
@@ -131,5 +131,5 @@ def __init__(self, description, package_name=None):
         self.message = self.description
 
         if package_name:
-            self.message += '\n' + 'package' + '=' + repr(self.arguments[package_name])
+            self.message += '\n' + 'package' + '=' + repr(self.package_name)
         super(PackageImportError, self).__init__(self.message)
diff --git a/qctrlopencontrols/qiskit/__init__.py b/qctrlopencontrols/qiskit/__init__.py
index 46850731..3d295c90 100644
--- a/qctrlopencontrols/qiskit/__init__.py
+++ b/qctrlopencontrols/qiskit/__init__.py
@@ -12,5 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""
+==============
+qiskit module
+==============
+"""
+
 # Minimum Qiskit version required
-qiskit_minimum_version = '0.10.0'
+QISKIT_MINIMUM_VERSION = '0.10.0'
diff --git a/qctrlopencontrols/qiskit/quantum_circuit.py b/qctrlopencontrols/qiskit/quantum_circuit.py
index 27354af7..fbaa98b1 100644
--- a/qctrlopencontrols/qiskit/quantum_circuit.py
+++ b/qctrlopencontrols/qiskit/quantum_circuit.py
@@ -21,7 +21,7 @@
 import numpy as np
 
 from ..globals import (FIX_DURATION_UNITARY, INSTANT_UNITARY)
-from ..qiskit import qiskit_minimum_version
+from ..qiskit import QISKIT_MINIMUM_VERSION
 from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
 from ..exceptions.exceptions import ArgumentsValueError, PackageImportError
 from ..utility.check_packages import check_package
@@ -101,7 +101,7 @@ def convert_dds_to_qiskit_quantum_circuit(
     any offset.
     """
 
-    check_package('qiskit-terra', qiskit_minimum_version)
+    check_package('qiskit-terra', QISKIT_MINIMUM_VERSION)
 
     try:
         from qiskit import (
diff --git a/qctrlopencontrols/utility/check_packages.py b/qctrlopencontrols/utility/check_packages.py
index 09f91ce1..b28dfda6 100644
--- a/qctrlopencontrols/utility/check_packages.py
+++ b/qctrlopencontrols/utility/check_packages.py
@@ -36,6 +36,13 @@ def check_package(package_name, minimum_package_version):
         The name of the package
     minimum_package_version: str
         The minimum version of the package
+
+    Raises
+    ------
+    PackageNotFoundError
+        If the required package is not found.
+    PackageVersionMismatchError
+        If the version of the package is found but lower than the minimum required.
     """
 
     try:

From aa92b77972b49105770c2cd8e5cf1cb83cd47bbb Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Sat, 26 Oct 2019 22:24:23 +1100
Subject: [PATCH 3/9] check_package location moved to base

---
 .../{utility => base}/check_packages.py             |  0
 qctrlopencontrols/qiskit/quantum_circuit.py         |  2 +-
 qctrlopencontrols/utility/__init__.py               | 13 -------------
 3 files changed, 1 insertion(+), 14 deletions(-)
 rename qctrlopencontrols/{utility => base}/check_packages.py (100%)
 delete mode 100644 qctrlopencontrols/utility/__init__.py

diff --git a/qctrlopencontrols/utility/check_packages.py b/qctrlopencontrols/base/check_packages.py
similarity index 100%
rename from qctrlopencontrols/utility/check_packages.py
rename to qctrlopencontrols/base/check_packages.py
diff --git a/qctrlopencontrols/qiskit/quantum_circuit.py b/qctrlopencontrols/qiskit/quantum_circuit.py
index fbaa98b1..7ce9426a 100644
--- a/qctrlopencontrols/qiskit/quantum_circuit.py
+++ b/qctrlopencontrols/qiskit/quantum_circuit.py
@@ -24,7 +24,7 @@
 from ..qiskit import QISKIT_MINIMUM_VERSION
 from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
 from ..exceptions.exceptions import ArgumentsValueError, PackageImportError
-from ..utility.check_packages import check_package
+from ..base.check_packages import check_package
 
 
 def convert_dds_to_qiskit_quantum_circuit(
diff --git a/qctrlopencontrols/utility/__init__.py b/qctrlopencontrols/utility/__init__.py
deleted file mode 100644
index a2b61496..00000000
--- a/qctrlopencontrols/utility/__init__.py
+++ /dev/null
@@ -1,13 +0,0 @@
-# Copyright 2019 Q-CTRL Pty Ltd & Q-CTRL Inc
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.

From 221312f60adbfad0ab9e77295212510ccfe3438f Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Sat, 26 Oct 2019 22:49:21 +1100
Subject: [PATCH 4/9] minor improvements

---
 qctrlopencontrols/qiskit/quantum_circuit.py | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/qctrlopencontrols/qiskit/quantum_circuit.py b/qctrlopencontrols/qiskit/quantum_circuit.py
index 7ce9426a..1cd73e29 100644
--- a/qctrlopencontrols/qiskit/quantum_circuit.py
+++ b/qctrlopencontrols/qiskit/quantum_circuit.py
@@ -180,8 +180,8 @@ def convert_dds_to_qiskit_quantum_circuit(
 
         if offset_distance < 0:
             raise ArgumentsValueError(
-                "Offsets cannot be placed properly. Spacing between the rotations"
-                "is smaller than the time required to perform the rotation. Provide"
+                "Offsets cannot be placed properly. Spacing between the rotations "
+                "is smaller than the time required to perform the rotation. Provide "
                 "a longer dynamic decoupling sequence or shorted gate time.",
                 {'dynamic_decoupling_sequence': dynamic_decoupling_sequence,
                  'gate_time': gate_time})
@@ -192,14 +192,11 @@ def convert_dds_to_qiskit_quantum_circuit(
                 quantum_circuit.barrier(quantum_registers[qubit])  # pylint: disable=no-member
             time_covered += gate_time
 
-        x_rotation = rabi_rotation * np.cos(azimuthal_angle)
-        y_rotation = rabi_rotation * np.sin(azimuthal_angle)
-        z_rotation = detuning_rotation
-
-        rotations = np.array([x_rotation, y_rotation, z_rotation])
-        zero_pulses = np.isclose(rotations, 0.0).astype(np.int)
-        nonzero_pulse_counts = 3 - np.sum(zero_pulses)
-        if nonzero_pulse_counts > 1:
+        rotations = np.array([rabi_rotation * np.cos(azimuthal_angle),
+                              rabi_rotation * np.sin(azimuthal_angle),
+                              detuning_rotation])
+        zero_pulse_count = np.sum(np.isclose(rotations, 0.0).astype(np.int))
+        if zero_pulse_count < 2:
             raise ArgumentsValueError(
                 'Open Controls support a sequence with one '
                 'valid rotation at any offset. Found a sequence '
@@ -212,7 +209,7 @@ def convert_dds_to_qiskit_quantum_circuit(
             )
 
         for qubit in target_qubits:
-            if nonzero_pulse_counts == 0:
+            if zero_pulse_count == 3:
                 quantum_circuit.u3(
                     0., 0., 0.,  # pylint: disable=no-member
                     quantum_registers[qubit])

From a92a08964d3e220146805853296c601a1c0542f9 Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Mon, 28 Oct 2019 10:51:37 +1100
Subject: [PATCH 5/9] minor change in docstring

---
 qctrlopencontrols/base/check_packages.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/qctrlopencontrols/base/check_packages.py b/qctrlopencontrols/base/check_packages.py
index b28dfda6..a719076b 100644
--- a/qctrlopencontrols/base/check_packages.py
+++ b/qctrlopencontrols/base/check_packages.py
@@ -27,8 +27,8 @@
 
 
 def check_package(package_name, minimum_package_version):
-    """Checks if the specified package and its minimum version
-    exists.
+    """Checks if the specified third party package and its minimum version
+    is available.
 
     Parameters
     ---------

From 289dfe5d5558fe41baaf39e4beb67eb27b5fa03f Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Mon, 28 Oct 2019 10:54:06 +1100
Subject: [PATCH 6/9] version constant made specific from qiskit to
 qiskit-terra

---
 qctrlopencontrols/qiskit/__init__.py        | 2 +-
 qctrlopencontrols/qiskit/quantum_circuit.py | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/qctrlopencontrols/qiskit/__init__.py b/qctrlopencontrols/qiskit/__init__.py
index 3d295c90..298cc281 100644
--- a/qctrlopencontrols/qiskit/__init__.py
+++ b/qctrlopencontrols/qiskit/__init__.py
@@ -19,4 +19,4 @@
 """
 
 # Minimum Qiskit version required
-QISKIT_MINIMUM_VERSION = '0.10.0'
+QISKIT_TERRA_MINIMUM_VERSION = '0.10.0'
diff --git a/qctrlopencontrols/qiskit/quantum_circuit.py b/qctrlopencontrols/qiskit/quantum_circuit.py
index 1cd73e29..d4f2a3f1 100644
--- a/qctrlopencontrols/qiskit/quantum_circuit.py
+++ b/qctrlopencontrols/qiskit/quantum_circuit.py
@@ -21,7 +21,7 @@
 import numpy as np
 
 from ..globals import (FIX_DURATION_UNITARY, INSTANT_UNITARY)
-from ..qiskit import QISKIT_MINIMUM_VERSION
+from ..qiskit import QISKIT_TERRA_MINIMUM_VERSION
 from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
 from ..exceptions.exceptions import ArgumentsValueError, PackageImportError
 from ..base.check_packages import check_package
@@ -101,7 +101,7 @@ def convert_dds_to_qiskit_quantum_circuit(
     any offset.
     """
 
-    check_package('qiskit-terra', QISKIT_MINIMUM_VERSION)
+    check_package('qiskit-terra', QISKIT_TERRA_MINIMUM_VERSION)
 
     try:
         from qiskit import (
@@ -109,7 +109,7 @@ def convert_dds_to_qiskit_quantum_circuit(
         from qiskit.qasm import pi
     except ImportError:
         raise PackageImportError(
-            'Error while trying to import Qiskit.'
+            'Error while trying to import qiskit-terra.'
         )
 
     if dynamic_decoupling_sequence is None:

From 3dc4d35b1ee4f6d447a81588dc237bc375bcf122 Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Mon, 28 Oct 2019 12:14:54 +1100
Subject: [PATCH 7/9] reduced the required minimum version of qiskit-terra

---
 qctrlopencontrols/qiskit/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qctrlopencontrols/qiskit/__init__.py b/qctrlopencontrols/qiskit/__init__.py
index 298cc281..d981b217 100644
--- a/qctrlopencontrols/qiskit/__init__.py
+++ b/qctrlopencontrols/qiskit/__init__.py
@@ -19,4 +19,4 @@
 """
 
 # Minimum Qiskit version required
-QISKIT_TERRA_MINIMUM_VERSION = '0.10.0'
+QISKIT_TERRA_MINIMUM_VERSION = '0.8.2'

From f329aebfe2337954428185544242461fe45c70aa Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Mon, 28 Oct 2019 12:24:34 +1100
Subject: [PATCH 8/9] reverted changes not related to lazy-loading

---
 qctrlopencontrols/qiskit/quantum_circuit.py | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/qctrlopencontrols/qiskit/quantum_circuit.py b/qctrlopencontrols/qiskit/quantum_circuit.py
index d4f2a3f1..fec757ab 100644
--- a/qctrlopencontrols/qiskit/quantum_circuit.py
+++ b/qctrlopencontrols/qiskit/quantum_circuit.py
@@ -180,8 +180,8 @@ def convert_dds_to_qiskit_quantum_circuit(
 
         if offset_distance < 0:
             raise ArgumentsValueError(
-                "Offsets cannot be placed properly. Spacing between the rotations "
-                "is smaller than the time required to perform the rotation. Provide "
+                "Offsets cannot be placed properly. Spacing between the rotations"
+                "is smaller than the time required to perform the rotation. Provide"
                 "a longer dynamic decoupling sequence or shorted gate time.",
                 {'dynamic_decoupling_sequence': dynamic_decoupling_sequence,
                  'gate_time': gate_time})
@@ -192,11 +192,14 @@ def convert_dds_to_qiskit_quantum_circuit(
                 quantum_circuit.barrier(quantum_registers[qubit])  # pylint: disable=no-member
             time_covered += gate_time
 
-        rotations = np.array([rabi_rotation * np.cos(azimuthal_angle),
-                              rabi_rotation * np.sin(azimuthal_angle),
-                              detuning_rotation])
-        zero_pulse_count = np.sum(np.isclose(rotations, 0.0).astype(np.int))
-        if zero_pulse_count < 2:
+        x_rotation = rabi_rotation * np.cos(azimuthal_angle)
+        y_rotation = rabi_rotation * np.sin(azimuthal_angle)
+        z_rotation = detuning_rotation
+
+        rotations = np.array([x_rotation, y_rotation, z_rotation])
+        zero_pulses = np.isclose(rotations, 0.0).astype(np.int)
+        nonzero_pulse_counts = 3 - np.sum(zero_pulses)
+        if nonzero_pulse_counts > 1:
             raise ArgumentsValueError(
                 'Open Controls support a sequence with one '
                 'valid rotation at any offset. Found a sequence '
@@ -209,7 +212,7 @@ def convert_dds_to_qiskit_quantum_circuit(
             )
 
         for qubit in target_qubits:
-            if zero_pulse_count == 3:
+            if nonzero_pulse_counts == 0:
                 quantum_circuit.u3(
                     0., 0., 0.,  # pylint: disable=no-member
                     quantum_registers[qubit])

From 3c9a7ae705520d136d61567abe89ec8197f7cc82 Mon Sep 17 00:00:00 2001
From: Rajib Chakravorty <rajib.chakravorty@q-ctrl.com>
Date: Mon, 28 Oct 2019 21:02:48 +1100
Subject: [PATCH 9/9] removed unnecessary exception definitions and
 check_package method; simply moved the imports  of the libraries inside the
 relevant methods

---
 qctrlopencontrols/base/check_packages.py    | 60 ----------------
 qctrlopencontrols/cirq/circuit.py           |  6 +-
 qctrlopencontrols/cirq/schedule.py          | 10 +--
 qctrlopencontrols/exceptions/exceptions.py  | 76 ---------------------
 qctrlopencontrols/pyquil/program.py         | 10 +--
 qctrlopencontrols/qiskit/__init__.py        |  9 ---
 qctrlopencontrols/qiskit/quantum_circuit.py | 23 ++-----
 7 files changed, 17 insertions(+), 177 deletions(-)
 delete mode 100644 qctrlopencontrols/base/check_packages.py

diff --git a/qctrlopencontrols/base/check_packages.py b/qctrlopencontrols/base/check_packages.py
deleted file mode 100644
index a719076b..00000000
--- a/qctrlopencontrols/base/check_packages.py
+++ /dev/null
@@ -1,60 +0,0 @@
-# Copyright 2019 Q-CTRL Pty Ltd & Q-CTRL Inc
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""
-Module with helper methods to check for third party packages.
-"""
-
-import pkg_resources
-from pkg_resources import DistributionNotFound
-from packaging.version import parse
-
-
-from qctrlopencontrols.exceptions.exceptions import (
-    PackageVersionMismatchError,
-    PackageNotFoundError)
-
-
-def check_package(package_name, minimum_package_version):
-    """Checks if the specified third party package and its minimum version
-    is available.
-
-    Parameters
-    ---------
-    package_name: str
-        The name of the package
-    minimum_package_version: str
-        The minimum version of the package
-
-    Raises
-    ------
-    PackageNotFoundError
-        If the required package is not found.
-    PackageVersionMismatchError
-        If the version of the package is found but lower than the minimum required.
-    """
-
-    try:
-        found_version = pkg_resources.get_distribution(package_name).version
-        if parse(found_version) < parse(minimum_package_version):
-            raise PackageVersionMismatchError(
-                'Minimum version of the {} package not found.'.format(package_name),
-                {'package name': package_name,
-                 'minimum package version': minimum_package_version},
-                extras={'version found': found_version})
-    except DistributionNotFound:
-        raise PackageNotFoundError(
-            'Package {} not found.'.format(package_name),
-            {'package name': package_name,
-             'minimum package version': minimum_package_version})
diff --git a/qctrlopencontrols/cirq/circuit.py b/qctrlopencontrols/cirq/circuit.py
index 8595946e..215b8451 100644
--- a/qctrlopencontrols/cirq/circuit.py
+++ b/qctrlopencontrols/cirq/circuit.py
@@ -20,14 +20,12 @@
 
 import numpy as np
 
-import cirq
-
 from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
 from ..exceptions.exceptions import ArgumentsValueError
 from ..globals import (FIX_DURATION_UNITARY, INSTANT_UNITARY)
 
 
-def convert_dds_to_cirq_circuit(
+def convert_dds_to_cirq_circuit(    #pylint: disable=too-many-locals
         dynamic_decoupling_sequence,
         target_qubits=None,
         gate_time=0.1,
@@ -93,6 +91,8 @@ def convert_dds_to_cirq_circuit(
     any offset.
     """
 
+    import cirq
+
     if dynamic_decoupling_sequence is None:
         raise ArgumentsValueError('No dynamic decoupling sequence provided.',
                                   {'dynamic_decoupling_sequence': dynamic_decoupling_sequence})
diff --git a/qctrlopencontrols/cirq/schedule.py b/qctrlopencontrols/cirq/schedule.py
index 88df4c10..689dd6e8 100644
--- a/qctrlopencontrols/cirq/schedule.py
+++ b/qctrlopencontrols/cirq/schedule.py
@@ -20,13 +20,11 @@
 
 import numpy as np
 
-import cirq
-
 from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
 from ..exceptions.exceptions import ArgumentsValueError
 
 
-def convert_dds_to_cirq_schedule(
+def convert_dds_to_cirq_schedule(   #pylint: disable=too-many-locals
         dynamic_decoupling_sequence,
         target_qubits=None,
         gate_time=0.1,
@@ -87,6 +85,8 @@ def convert_dds_to_cirq_schedule(
     any offset.
     """
 
+    import cirq
+
     if dynamic_decoupling_sequence is None:
         raise ArgumentsValueError('No dynamic decoupling sequence provided.',
                                   {'dynamic_decoupling_sequence': dynamic_decoupling_sequence})
@@ -146,8 +146,8 @@ def convert_dds_to_cirq_schedule(
         nonzero_pulse_counts = 3 - np.sum(zero_pulses)
         if nonzero_pulse_counts > 1:
             raise ArgumentsValueError(
-                'Open Controls support a sequence with one '
-                'valid pulse at any offset. Found sequence '
+                'Open Controls support a sequence with one'
+                'valid pulse at any offset. Found sequence'
                 'with multiple rotation operations at an offset.',
                 {'dynamic_decoupling_sequence': str(dynamic_decoupling_sequence),
                  'offset': dynamic_decoupling_sequence.offsets[op_idx],
diff --git a/qctrlopencontrols/exceptions/exceptions.py b/qctrlopencontrols/exceptions/exceptions.py
index dd075304..c68c6d98 100644
--- a/qctrlopencontrols/exceptions/exceptions.py
+++ b/qctrlopencontrols/exceptions/exceptions.py
@@ -57,79 +57,3 @@ def __init__(self, description, arguments, extras=None):
             for key in self.extras:
                 self.message += '\n' + str(key) + '=' + repr(self.extras[key])
         super(ArgumentsValueError, self).__init__(self.message)
-
-
-class PackageVersionMismatchError(QctrlError):
-    """Exception raised when the version of required third party packages found but is
-    below the minimum required.
-
-    Parameters
-    ----------
-    description : string
-        Description of the why the error is raised.
-    arguments : dict
-        Dictionary that contains the package name, required minimum version.
-    extras : dict, optional
-        Other variables, such as the version found in the system,
-        that may be relevant to the error. Defaults to None.
-    """
-
-    def __init__(self, description, arguments, extras=None):
-        self.description = description
-        self.arguments = arguments
-        self.extras = extras
-        self.message = self.description
-
-        for key in self.arguments:
-            self.message += '\n' + str(key) + '=' + repr(self.arguments[key])
-        if extras is not None:
-            for key in self.extras:
-                self.message += '\n' + str(key) + '=' + repr(self.extras[key])
-        super(PackageVersionMismatchError, self).__init__(self.message)
-
-
-class PackageNotFoundError(QctrlError):
-    """Exception raised when the required third party packages is not found.
-
-    Parameters
-    ----------
-    description : string
-        Description of the why the error is raised.
-    arguments : dict
-        Dictionary that contains the package name and the required minimum version.
-    extras : dict, optional
-        Other variables that may be relevant to the error. Defaults to None.
-    """
-
-    def __init__(self, description, arguments, extras=None):
-        self.description = description
-        self.arguments = arguments
-        self.extras = extras
-        self.message = self.description
-
-        for key in self.arguments:
-            self.message += '\n' + str(key) + '=' + repr(self.arguments[key])
-        if extras is not None:
-            for key in self.extras:
-                self.message += '\n' + str(key) + '=' + repr(self.extras[key])
-        super(PackageNotFoundError, self).__init__(self.message)
-
-
-class PackageImportError(QctrlError):
-    """Exception raised when a package cannot be imported.
-
-    Parameters
-    ----------
-    description : string
-        Description of the why the error is raised.
-    package_name : string, optional
-        The name of the package that could not be imported. Defaults to None.
-    """
-    def __init__(self, description, package_name=None):
-        self.description = description
-        self.package_name = package_name
-        self.message = self.description
-
-        if package_name:
-            self.message += '\n' + 'package' + '=' + repr(self.package_name)
-        super(PackageImportError, self).__init__(self.message)
diff --git a/qctrlopencontrols/pyquil/program.py b/qctrlopencontrols/pyquil/program.py
index 52e18a29..ee611a02 100644
--- a/qctrlopencontrols/pyquil/program.py
+++ b/qctrlopencontrols/pyquil/program.py
@@ -20,17 +20,13 @@
 
 import numpy as np
 
-from pyquil import Program
-from pyquil.gates import I, RX, RY, RZ, MEASURE
-from pyquil.quil import Pragma
-
 from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
 from ..exceptions.exceptions import ArgumentsValueError
 from ..globals import (
     FIX_DURATION_UNITARY, INSTANT_UNITARY)
 
 
-def convert_dds_to_pyquil_program(
+def convert_dds_to_pyquil_program(  #pylint: disable=too-many-locals
         dynamic_decoupling_sequence,
         target_qubits=None,
         gate_time=0.1,
@@ -93,6 +89,10 @@ def convert_dds_to_pyquil_program(
     any offset.
     """
 
+    from pyquil import Program
+    from pyquil.gates import I, RX, RY, RZ, MEASURE
+    from pyquil.quil import Pragma
+
     if dynamic_decoupling_sequence is None:
         raise ArgumentsValueError('No dynamic decoupling sequence provided.',
                                   {'dynamic_decoupling_sequence': dynamic_decoupling_sequence})
diff --git a/qctrlopencontrols/qiskit/__init__.py b/qctrlopencontrols/qiskit/__init__.py
index d981b217..a2b61496 100644
--- a/qctrlopencontrols/qiskit/__init__.py
+++ b/qctrlopencontrols/qiskit/__init__.py
@@ -11,12 +11,3 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-"""
-==============
-qiskit module
-==============
-"""
-
-# Minimum Qiskit version required
-QISKIT_TERRA_MINIMUM_VERSION = '0.8.2'
diff --git a/qctrlopencontrols/qiskit/quantum_circuit.py b/qctrlopencontrols/qiskit/quantum_circuit.py
index d4f2a3f1..5cd7e88d 100644
--- a/qctrlopencontrols/qiskit/quantum_circuit.py
+++ b/qctrlopencontrols/qiskit/quantum_circuit.py
@@ -21,10 +21,8 @@
 import numpy as np
 
 from ..globals import (FIX_DURATION_UNITARY, INSTANT_UNITARY)
-from ..qiskit import QISKIT_TERRA_MINIMUM_VERSION
 from ..dynamic_decoupling_sequences.dynamic_decoupling_sequence import DynamicDecouplingSequence
-from ..exceptions.exceptions import ArgumentsValueError, PackageImportError
-from ..base.check_packages import check_package
+from ..exceptions.exceptions import ArgumentsValueError
 
 
 def convert_dds_to_qiskit_quantum_circuit(
@@ -73,12 +71,6 @@ def convert_dds_to_qiskit_quantum_circuit(
     ------
     ArgumentsValueError
         If any of the input parameters are invalid
-    PackageNotFoundError
-        If Qiskit is not found
-    PackageVersionMismatchError
-        If the required minimum version of Qiskit is not found
-    PackageImportError
-        If Qiskit cannot be imported
 
     Notes
     -----
@@ -101,16 +93,9 @@ def convert_dds_to_qiskit_quantum_circuit(
     any offset.
     """
 
-    check_package('qiskit-terra', QISKIT_TERRA_MINIMUM_VERSION)
-
-    try:
-        from qiskit import (
-            QuantumRegister, ClassicalRegister, QuantumCircuit)
-        from qiskit.qasm import pi
-    except ImportError:
-        raise PackageImportError(
-            'Error while trying to import qiskit-terra.'
-        )
+    from qiskit import (
+        QuantumRegister, ClassicalRegister, QuantumCircuit)
+    from qiskit.qasm import pi
 
     if dynamic_decoupling_sequence is None:
         raise ArgumentsValueError('No dynamic decoupling sequence provided.',