Merge branch '367-generate-initial-live-points-in-dynesty' into 'master'

Resolve "Generate initial live points in dynesty"

Closes #367

See merge request !488

bilby/core/sampler/base_sampler.py

@@ -388,12 +388,62 @@ class Sampler(object):
         self.check_draw(draw)
         return draw
 
-    def check_draw(self, draw):
-        """ Checks if the draw will generate an infinite prior or likelihood """
-        if np.isinf(self.log_likelihood(draw)):
-            logger.warning('Prior draw {} has inf likelihood'.format(draw))
-        if np.isinf(self.log_prior(draw)):
-            logger.warning('Prior draw {} has inf prior'.format(draw))
+    def get_initial_points_from_prior(self, npoints=1):
+        """ Method to draw a set of live points from the prior
+
+        This iterates over draws from the prior until all the samples have a
+        finite prior and likelihood (relevant for constrained priors).
+
+        Parameters
+        ----------
+        npoints: int
+            The number of values to return
+
+        Returns
+        -------
+        unit_cube, parameters, likelihood: tuple of array_like
+            unit_cube (nlive, ndim) is an array of the prior samples from the
+            unit cube, parameters (nlive, ndim) is the unit_cube array
+            transformed to the target space, while likelihood (nlive) are the
+            likelihood evaluations.
+
+        """
+        unit_cube = []
+        parameters = []
+        likelihood = []
+        while len(unit_cube) < npoints:
+            unit = np.random.rand(self.ndim)
+            theta = self.prior_transform(unit)
+            if self.check_draw(theta, warning=False):
+                unit_cube.append(unit)
+                parameters.append(theta)
+                likelihood.append(self.log_likelihood(theta))
+
+        return np.array(unit_cube), np.array(parameters), np.array(likelihood)
+
+    def check_draw(self, theta, warning=True):
+        """ Checks if the draw will generate an infinite prior or likelihood
+
+        Parameters
+        ----------
+        theta: array_like
+            Parameter values at which to evaluate likelihood
+
+        Returns
+        -------
+        bool, cube (nlive,
+            True if the likelihood and prior are finite, false otherwise
+
+        """
+        if np.isinf(self.log_prior(theta)):
+            if warning:
+                logger.warning('Prior draw {} has inf prior'.format(theta))
+            return False
+        if np.isinf(self.log_likelihood(theta)):
+            if warning:
+                logger.warning('Prior draw {} has inf likelihood'.format(theta))
+            return False
+        return True
 
     def run_sampler(self):
         """A template method to run in subclasses"""

bilby/core/sampler/dynesty.py

@@ -202,6 +202,10 @@ class Dynesty(NestedSampler):
 
     def run_sampler(self):
         import dynesty
+        if self.kwargs['live_points'] is None:
+            self.kwargs['live_points'] = (
+                self.get_initial_points_from_prior(
+                    self.kwargs['nlive']))
         self.sampler = dynesty.NestedSampler(
             loglikelihood=self.log_likelihood,
             prior_transform=self.prior_transform,