From 491309177a950e035fa9fd38187876b1ab01831b Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Mon, 12 Jun 2017 15:44:06 -0500
Subject: [PATCH] Expose tally results array via numpy array

---
 openmc/libopenmc.py | 31 ++++++++++++++++++++++++++++++-
 src/tally.F90       | 16 ++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/openmc/libopenmc.py b/openmc/libopenmc.py
index c5dfc1f2fd..f95f72aac6 100644
--- a/openmc/libopenmc.py
+++ b/openmc/libopenmc.py
@@ -1,7 +1,10 @@
-from ctypes import CDLL, c_int, POINTER, byref
+from ctypes import CDLL, c_int, POINTER, byref, c_double
 import sys
 from warnings import warn
 
+import numpy as np
+from numpy.ctypeslib import ndpointer, as_array
+
 import pkg_resources
 
 
@@ -17,6 +20,10 @@ class _OpenMCLibrary(object):
         self._dll.openmc_calculate_volumes.restype = None
         self._dll.openmc_finalize.restype = None
         self._dll.openmc_reset.restype = None
+        self._dll.openmc_tally_results.argtypes = [
+            c_int, POINTER(POINTER(c_double)), ndpointer(
+                np.intc, shape=(3,))]
+        self._dll.openmc_tally_results.restype = None
 
     def init(self, intracomm=None):
         """Initialize OpenMC
@@ -58,6 +65,28 @@ class _OpenMCLibrary(object):
         """Reset tallies"""
         return self._dll.openmc_reset()
 
+    def tally_results(self, tally_id):
+        """Get tally results array
+
+        Parameters
+        ----------
+        tally_id : int
+            ID of tally
+
+        Returns
+        -------
+        numpy.ndarray
+            Array that exposes the internal tally results array
+
+        """
+        r_p = POINTER(c_double)()
+        r_shape = np.zeros(3, np.intc)
+        self._dll.openmc_tally_results(tally_id, byref(r_p), r_shape)
+        if r_p:
+            return as_array(r_p, tuple(r_shape[::-1]))
+        else:
+            return None
+
     def __getattr__(self, key):
         # Fall-back for other functions that may be available from library
         try:
diff --git a/src/tally.F90 b/src/tally.F90
index 14940551b7..f2dd3b1079 100644
--- a/src/tally.F90
+++ b/src/tally.F90
@@ -4430,4 +4430,20 @@ contains
 
   end subroutine setup_active_cmfdtallies
 
+  subroutine openmc_tally_results(i, ptr, shape_) bind(C)
+    integer(C_INT), intent(in), value :: i
+    type(C_PTR),    intent(out) :: ptr
+    integer(C_INT), intent(out) :: shape_(3)
+
+    ptr = C_NULL_PTR
+    if (allocated(tallies)) then
+      if (i >= 1 .and. i <= size(tallies)) then
+        if (allocated(tallies(i) % results)) then
+          ptr = C_LOC(tallies(i) % results(1,1,1))
+          shape_(:) = shape(tallies(i) % results)
+        end if
+      end if
+    end if
+  end subroutine openmc_tally_results
+
 end module tally