Added ensemble object

scisample/ensemble.py

@@ -0,0 +1,95 @@
+"""
+Module defining an ensemble, which contains multiple samplers joined together.
+
+Follows the same interface as the samplers.
+"""
+import logging
+
+from scisample.base_sampler import BaseSampler
+from scisample.samplers import new_sampler
+from scisample.utils import log_and_raise_exception
+
+LOG = logging.getLogger(__name__)
+
+
+class Ensemble(BaseSampler):
+    """
+    Class for combining multiple samplers.
+    """
+
+    def __init__(self, *sampler_data):
+        """
+        Initialize the sampler.
+
+        :param sampler_data: Sampler data to use to initialize the samplers.
+        """
+        super(Ensemble, self).__init__(sampler_data)
+
+        self._samplers = []
+        for data in sampler_data:
+            if not isinstance(data, list):
+                data = [data]
+            self.add_samplers(*data)
+
+        self.check_validity()
+
+    def add_samplers(self, *sampler_data):
+        """
+        Add additional samplers to the Ensemble.
+        A validity check will be performed after adding samples.
+        Additionally, the samples will be un-cached from the Ensemble.
+        (sampler caches will not be impacted).
+
+        :param sampler_data: Sampler data to use to add samplers.
+        """
+        for data in sampler_data:
+            self._samplers.append(new_sampler(data))
+        self.check_validity()
+        self._samples = None
+        self._parameter_block = None
+
+    def check_validity(self):
+        """
+        Check the validity of the underlying samplers.
+        """
+        if not self._samplers:
+            log_and_raise_exception(
+                "No samplers requested for ensemble"
+            )
+        for sampler in self._samplers:
+            sampler.check_validity()
+            if sorted(self.parameters) != sorted(sampler.parameters):
+                log_and_raise_exception(
+                    "All samplers in an ensemble must have the same "
+                    f"parameters.  Parameters from {sampler.parameters} "
+                    f"did not match {self.parameters}."
+                )
+
+    @property
+    def parameters(self):
+        """
+        Return a of list of the parameters being generated by the
+        sampler.
+        """
+        return self._samplers[0].parameters
+
+    def get_samples(self):
+        """
+        Get samples from the samplers.
+
+        This returns samples as a list of dictionaries, with the
+        sample variables as the keys:
+
+        .. code:: python
+
+            [{'b': 0.89856, 'a': 1}, {'b': 0.923223, 'a': 1}, ... ]
+        """
+        LOG.info("Entering Ensemble.get_samples()")
+        if self._samples is not None:
+            return self._samples
+
+        self._samples = []
+        for sampler in self._samplers:
+            self._samples.extend(sampler.get_samples())
+
+        return self._samples