Fix/svc kernel

examples/ERP/plot_classify_P300_bi.py

@@ -67,7 +67,7 @@
 
 # reduce the number of subjects, the Quantum pipeline takes a lot of time
 # if executed on the entire dataset
-n_subjects = 5
+n_subjects = 2
 for dataset in datasets:
     dataset.subject_list = dataset.subject_list[0:n_subjects]
 
@@ -78,7 +78,7 @@
 # A Riemannian Quantum pipeline provided by pyRiemann-qiskit
 # You can choose between classical SVM and Quantum SVM.
 pipelines["RG+QuantumSVM"] = QuantumClassifierWithDefaultRiemannianPipeline(
-    shots=None,  # 'None' forces classic SVM
+    shots=512,  # 'None' forces classic SVM
     nfilter=2,  # default 2
     # default n_components=10, a higher value renders better performance with
     # the non-qunatum SVM version used in qiskit

examples/MI/plot_compare_dim_red.py

@@ -39,10 +39,6 @@
     # Determine the number of "run" on the quantum machine (simulated or real)
     # the higher is this number, the lower the variability.
     "shots": [1024],  # [512, 1024, 2048]
-    # This defines how we entangle the data into a quantum state
-    # the more complex is the kernel, the more outcomes we can expect from
-    # a quantum vs classical classifier.
-    "feature_entanglement": ["linear"],  # ['linear', 'sca', 'full'],
     # This parameter change the depth of the circuit when entangling data.
     # There is a trade-off between accuracy and noise when the depth of the
     # circuit increases.

pyriemann_qiskit/classification.py

@@ -5,6 +5,7 @@
 quantum computer.
 """
 from datetime import datetime
+from scipy.special import softmax
 import logging
 import numpy as np
 
@@ -149,7 +150,7 @@ def _map_indices_to_classes(self, y):
         n_classes = len(self.classes_)
         for idx in range(n_classes):
             y_copy[y == idx] = self.classes_[idx]
-        return y_copy
+        return np.array(y_copy)
 
     def fit(self, X, y):
         """Uses a quantum backend and fits the training data.
@@ -237,6 +238,49 @@ def _predict(self, X):
         self._log("Prediction finished.")
         return result
 
+    def predict_proba(self, X):
+        """Return the probabilities associated with predictions.
+
+        The default behavior is to return the nested classifier probabilities.
+        In case where no `predict_proba` method is available inside the classifier,
+        the method the predicted label number (0 or 1 for examples) and applies a
+        softmax in top of it.
+
+        Parameters
+        ----------
+        X : ndarray, shape (n_samples, n_features)
+            Input vector, where `n_samples` is the number of samples and
+            `n_features` is the number of features.
+
+        Returns
+        -------
+        prob : ndarray, shape (n_samples, n_classes)
+            prob[n, i] == 1 if the nth sample is assigned to class `i`;
+        """
+
+        if not hasattr(self._classifier, "predict_proba"):
+            # Classifier has no predict_proba
+            # Use the result from predict and apply a softmax
+            self._log(
+                "No predict_proba method available.\
+                       Computing softmax probabilities..."
+            )
+            proba = self._classifier.predict(X)
+            proba = [
+                np.array(
+                    [
+                        1 if c == self.classes_[i] else 0
+                        for i in range(len(self.classes_))
+                    ]
+                )
+                for c in proba
+            ]
+            proba = softmax(proba, axis=0)
+        else:
+            proba = self._classifier.predict_proba(X)
+
+        return np.array(proba)
+
 
 class QuanticSVM(QuanticClassifierBase):
 
@@ -256,6 +300,8 @@ class QuanticSVM(QuanticClassifierBase):
         Fix: copy estimator not keeping base class parameters.
     .. versionchanged:: 0.2.0
         Add seed parameter
+        SVC and QSVC now compute probability (may impact time performance)
+        Predict is now using predict_proba with a softmax, when using QSVC.
 
     Parameters
     ----------
@@ -360,10 +406,13 @@ def _init_algo(self, n_features):
                     gamma=self.gamma,
                     C=self.C,
                     max_iter=max_iter,
+                    probability=True,
                 )
         else:
             max_iter = -1 if self.max_iter is None else self.max_iter
-            classifier = SVC(gamma=self.gamma, C=self.C, max_iter=max_iter)
+            classifier = SVC(
+                gamma=self.gamma, C=self.C, max_iter=max_iter, probability=True
+            )
         return classifier
 
     def predict_proba(self, X):
@@ -383,15 +432,15 @@ def predict_proba(self, X):
         Returns
         -------
         prob : ndarray, shape (n_samples, n_classes)
-            prob[n, 0] == True if the nth sample is assigned to 1st class;
-            prob[n, 1] == True if the nth sample is assigned to 2nd class.
+            prob[n, i] == 1 if the nth sample is assigned to class `i`;
         """
-        predicted_labels = self.predict(X)
-        ret = [
-            np.array([c == self.classes_[0], c == self.classes_[1]])
-            for c in predicted_labels
-        ]
-        return np.array(ret)
+
+        proba = super().predict_proba(X)
+        if isinstance(self._classifier, QSVC):
+            # apply additional softmax
+            proba = softmax(proba)
+
+        return np.array(proba)
 
     def predict(self, X):
         """Calculates the predictions.
@@ -407,7 +456,12 @@ def predict(self, X):
         pred : array, shape (n_samples,)
             Class labels for samples in X.
         """
-        labels = self._predict(X)
+        if isinstance(self._classifier, QSVC):
+            probs = self.predict_proba(X)
+            labels = [np.argmax(prob) for prob in probs]
+        else:
+            labels = self._predict(X)
+        self._log("Prediction finished.")
         return self._map_indices_to_classes(labels)
 
 
@@ -514,24 +568,6 @@ def _init_algo(self, n_features):
         )
         return vqc
 
-    def predict_proba(self, X):
-        """Returns the probabilities associated with predictions.
-
-        Parameters
-        ----------
-        X : ndarray, shape (n_samples, n_features)
-            Input vector, where `n_samples` is the number of samples and
-            `n_features` is the number of features.
-
-        Returns
-        -------
-        prob : ndarray, shape (n_samples, n_classes)
-            prob[n, 0] == True if the nth sample is assigned to 1st class;
-            prob[n, 1] == True if the nth sample is assigned to 2nd class.
-        """
-        proba, _ = self._predict(X)
-        return proba
-
     def predict(self, X):
         """Calculates the predictions.
 
@@ -664,22 +700,6 @@ def _init_algo(self, n_features):
         set_global_optimizer(self._optimizer)
         return classifier
 
-    def predict_proba(self, X):
-        """Return the probabilities associated with predictions.
-
-        Parameters
-        ----------
-        X : ndarray, shape (n_trials, n_channels, n_channels)
-            ndarray of trials.
-
-        Returns
-        -------
-        prob : ndarray, shape (n_samples, n_classes)
-            prob[n, 0] == True if the nth sample is assigned to 1st class;
-            prob[n, 1] == True if the nth sample is assigned to 2nd class.
-        """
-        return self._classifier.predict_proba(X)
-
     def predict(self, X):
         """Calculates the predictions.
 

pyriemann_qiskit/pipelines.py

@@ -10,6 +10,7 @@
 from pyriemann_qiskit.utils.filtering import NoDimRed
 from pyriemann_qiskit.utils.hyper_params_factory import (
     gen_zz_feature_map,
+    gen_x_feature_map,
     gen_two_local,
     get_spsa,
 )
@@ -175,12 +176,6 @@ class QuantumClassifierWithDefaultRiemannianPipeline(BasePipeline):
     shots : int | None (default: 1024)
         Number of repetitions of each circuit, for sampling.
         If None, classical computation will be performed.
-    feature_entanglement : str | list[list[list[int]]] | \
-                   Callable[int, list[list[list[int]]]]
-        Specifies the entanglement structure for the ZZFeatureMap.
-        Entanglement structure can be provided with indices or string.
-        Possible string values are: 'full', 'linear', 'circular' and 'sca'.
-        See [2]_ for more details on entanglement structure.
     feature_reps : int (default: 2)
         The number of repeated circuits for the ZZFeatureMap,
         greater or equal to 1.
@@ -206,12 +201,15 @@ class QuantumClassifierWithDefaultRiemannianPipeline(BasePipeline):
     Notes
     -----
     .. versionadded:: 0.0.1
+    .. versionchanged:: 0.2.0
+        Change feature map from ZZFeatureMap to XFeatureMap.
+        Therefore remove unused parameter `feature_entanglement`.
 
     See Also
     --------
     XdawnCovariances
     TangentSpace
-    gen_zz_feature_map
+    gen_x_feature_map
     gen_two_local
     get_spsa
     QuanticVQC
@@ -236,7 +234,6 @@ def __init__(
         C=1.0,
         max_iter=None,
         shots=1024,
-        feature_entanglement="full",
         feature_reps=2,
         spsa_trials=None,
         two_local_reps=None,
@@ -248,7 +245,6 @@ def __init__(
         self.C = C
         self.max_iter = max_iter
         self.shots = shots
-        self.feature_entanglement = feature_entanglement
         self.feature_reps = feature_reps
         self.spsa_trials = spsa_trials
         self.two_local_reps = two_local_reps
@@ -261,7 +257,7 @@ def _create_pipe(self):
         is_vqc = self.spsa_trials and self.two_local_reps
         is_quantum = self.shots is not None
 
-        feature_map = gen_zz_feature_map(self.feature_reps, self.feature_entanglement)
+        feature_map = gen_x_feature_map(self.feature_reps)
 
         if is_vqc:
             self._log("QuanticVQC chosen.")
@@ -320,7 +316,7 @@ class QuantumMDMWithRiemannianPipeline(BasePipeline):
     shots : int (default:1024)
         Number of repetitions of each circuit, for sampling.
     gen_feature_map : Callable[int, QuantumCircuit | FeatureMap] \
-                      (default : Callable[int, ZZFeatureMap])
+                      (default : Callable[int, XFeatureMap])
         Function generating a feature map to encode data into a quantum state.
 
     Attributes

tests/conftest.py

@@ -100,8 +100,9 @@ def _get_dataset(n_samples, n_features, n_classes, type="bin"):
             samples_0 = make_covariances(
                 n_samples // n_classes, n_features, 0, return_params=False
             )
-            samples_1 = samples_0 * 2
-            samples = np.concatenate((samples_0, samples_1), axis=0)
+            samples = np.concatenate(
+                [samples_0 * (i + 1) for i in range(n_classes)], axis=0
+            )
             labels = _get_labels(n_samples, n_classes)
         else:
             samples, labels = get_mne_sample()
@@ -179,6 +180,7 @@ class BinaryFVT(BinaryTest):
     def additional_steps(self):
         self.quantum_instance.fit(self.samples, self.labels)
         self.prediction = self.quantum_instance.predict(self.samples)
+        self.predict_proab = self.quantum_instance.predict_proba(self.samples)
         print(self.labels, self.prediction)
 
 

tests/test_classification.py

@@ -114,12 +114,10 @@ def get_params(self):
         }
 
     def check(self):
-        assert (
-            self.prediction[: self.class_len].all() == self.quantum_instance.classes_[0]
-        )
-        assert (
-            self.prediction[self.class_len :].all() == self.quantum_instance.classes_[1]
-        )
+        # Check that all classes are predicted
+        assert len(self.prediction) == len(self.labels)
+        # Check the proba for each classes are returned
+        assert self.predict_proab.shape[1] == len(np.unique(self.labels))
 
 
 class TestQuanticSVM(TestClassicalSVM):
@@ -141,6 +139,17 @@ def get_params(self):
         }
 
 
+class TestQuanticSVM_MultiClass(MultiClassFVT):
+    """Perform SVM on a simulated quantum computer
+    (multi-label classification)"""
+
+    def get_params(self):
+        return TestQuanticSVM.get_params(self)
+
+    def check(self):
+        TestQuanticSVM.check(self)
+
+
 class TestQuanticPegasosSVM(TestClassicalSVM):
     """Same as TestQuanticSVM, except it uses
     PegasosQSVC instead of QSVC implementation.
@@ -176,6 +185,8 @@ def check(self):
         assert len(self.prediction) == len(self.labels)
         # Check the number of classes is consistent
         assert len(np.unique(self.prediction)) == len(np.unique(self.labels))
+        # Check the proba for each classes are returned
+        assert self.predict_proab.shape[1] == len(np.unique(self.labels))
 
 
 class TestQuanticVQC_MultiClass(MultiClassFVT):
@@ -207,9 +218,19 @@ def get_params(self):
         }
 
     def check(self):
-        assert (
-            self.prediction[: self.class_len].all() == self.quantum_instance.classes_[0]
-        )
-        assert (
-            self.prediction[self.class_len :].all() == self.quantum_instance.classes_[1]
-        )
+        assert len(self.prediction) == len(self.labels)
+        # Check the number of classes is consistent
+        assert len(np.unique(self.prediction)) == len(np.unique(self.labels))
+        # Check the proba for each classes are returned
+        assert self.predict_proab.shape[1] == len(np.unique(self.labels))
+
+
+class TestQuanticMDM_MultiClass(MultiClassFVT):
+    """Perform MDM on a simulated quantum computer
+    (multi-label classification)"""
+
+    def get_params(self):
+        return TestClassicalMDM.get_params(self)
+
+    def check(self):
+        TestClassicalMDM.check(self)