From 05b600819aee5e3be8dd77bc6bf059acf562c63c Mon Sep 17 00:00:00 2001
From: Adam Nelson <nelsonag@umich.edu>
Date: Thu, 7 Jan 2016 20:20:55 -0500
Subject: [PATCH] Updates to MGXS pyapi

---
 openmc/material.py     |  3 +--
 openmc/mgxs_library.py | 25 ++++++++++++++++++-------
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/openmc/material.py b/openmc/material.py
index 4da4e0ae35..ca78bd61f2 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -339,8 +339,7 @@ class Material(object):
 
         # Ensure no nuclides, elements, or sab are added since these would be
         # incompatible with macroscopics
-        if ((len(self._nuclides.keys()) != 0) and
-            (len(self._elements.keys()) != 0) and (len(self._sab) != 0)):
+        if self._nuclides or self._elements or self._sab:
             msg = 'Unable to add a Macroscopic data set to Material ID="{0}" ' \
                   'with a macroscopic value "{1}" as an incompatible data ' \
                   'member (i.e., nuclide, element, or S(a,b) table) ' \
diff --git a/openmc/mgxs_library.py b/openmc/mgxs_library.py
index d1c1f4e05f..5820c0ee52 100644
--- a/openmc/mgxs_library.py
+++ b/openmc/mgxs_library.py
@@ -20,6 +20,17 @@ REPRESENTATIONS = ['isotropic', 'angle']
 def ndarray_to_string(arr):
     """Converts a numpy ndarray in to a join with spaces between entries
     similar to ' '.join(map(str,arr)) but applied to all sub-dimensions.
+
+    Parameters
+    ----------
+    arr : ndarray
+        Array to combine in to a string
+
+    Returns
+    -------
+    text : str
+        String representation of array in arr
+
     """
 
     shape = arr.shape
@@ -67,8 +78,8 @@ def ndarray_to_string(arr):
     return text
 
 
-class Xsdata(object):
-    """A multi-group cross section data set (xsdata) providing all the
+class XSdata(object):
+    """A multi-group cross section data set providing all the
     multi-group data necessary for a multi-group OpenMC calculation.
 
     Parameters
@@ -76,7 +87,6 @@ class Xsdata(object):
     name : str, optional
         Name of the mgxs data set.
 
-
     representation : str
         Method used in generating the MGXS (isotropic or angle-dependent flux
         weighting). Defaults to 'isotropic'
@@ -141,7 +151,6 @@ class Xsdata(object):
     def representation(self):
         return self._representation
 
-
     @property
     def alias(self):
         return self._alias
@@ -221,8 +230,8 @@ class Xsdata(object):
         check_type("energy_groups", energy_groups, EnergyGroups)
 
         # Check that there is one or more groups
-        if ((energy_groups.num_energy_groups.num_group is None) or
-            (energy_groups.num_energy_groups.num_group < 1)):
+        if ((energy_groups.num_groups is None) or
+            (energy_groups.num_groups < 1)):
 
             msg = 'energy_groups object incorrectly initialized.'
             raise ValueError(msg)
@@ -429,7 +438,7 @@ class Xsdata(object):
 
     @nu_fission.setter
     def nu_fission(self, nu_fission):
-        # nu_fission ca nbe given as a vector or a matrix
+        # nu_fission can be given as a vector or a matrix
         # Vector is used when chi also exists.
         # Matrix is used when chi does not exist.
         # We have to check that the correct form is given, but only if
@@ -563,6 +572,8 @@ class MGXSLibraryFile(object):
         Inverse of velocities, units of sec/cm
     filename : str
         XML file to write to.
+    xsdatas : Iterable of XSdata
+        Iterable of multi-Group cross section data objects
     """
 
     def __init__(self, energy_groups):