Merge branch 'parallizing_mirrored_samples' into 'NIFTy_5'

parallelization for mirrored KL

See merge request ift/nifty!301

nifty5/minimization/metric_gaussian_kl_mpi.py

@@ -59,7 +59,7 @@ def allreduce_sum_field(fld):
 class MetricGaussianKL_MPI(Energy):
     def __init__(self, mean, hamiltonian, n_samples, constants=[],
                  point_estimates=[], mirror_samples=False,
-                 _samples=None):
+                 _samples=None, seed_offset=0):
         super(MetricGaussianKL_MPI, self).__init__(mean)
 
         if not isinstance(hamiltonian, StandardHamiltonian):
@@ -76,18 +76,30 @@ class MetricGaussianKL_MPI(Energy):
         self._hamiltonian = hamiltonian
 
         if _samples is None:
-            lo, hi = _shareRange(n_samples, ntask, rank)
+            if mirror_samples:
+                lo, hi = _shareRange(n_samples*2, ntask, rank)
+            else:
+                lo, hi = _shareRange(n_samples, ntask, rank)
             met = hamiltonian(Linearization.make_partial_var(
                 mean, point_estimates, True)).metric
             _samples = []
             for i in range(lo, hi):
-                np.random.seed(i)
-                _samples.append(met.draw_sample(from_inverse=True))
+                if mirror_samples:
+                    np.random.seed(i//2+seed_offset)
+                    if (i % 2) and (i-1 >= lo):
+                        _samples.append(-_samples[-1])
+
+                    else:
+                        _samples.append(((i % 2)*2-1) *
+                                        met.draw_sample(from_inverse=True))
+                else:
+                    np.random.seed(i)
+                    _samples.append(met.draw_sample(from_inverse=True))
+            _samples = tuple(_samples)
             if mirror_samples:
-                _samples += [-s for s in _samples]
                 n_samples *= 2
-            _samples = tuple(_samples)
         self._samples = _samples
+        self._seed_offset = seed_offset
         self._n_samples = n_samples
         self._lin = Linearization.make_partial_var(mean, constants)
         v, g = None, None
@@ -111,7 +123,8 @@ class MetricGaussianKL_MPI(Energy):
     def at(self, position):
         return MetricGaussianKL_MPI(
             position, self._hamiltonian, self._n_samples, self._constants,
-            self._point_estimates, _samples=self._samples)
+            self._point_estimates, _samples=self._samples,
+            seed_offset=self._seed_offset)
 
     @property
     def value(self):