Merge pull request #754 from nelsonag/function

Additions to openmc.data.Function1D and openmc.data.DataLibrary

openmc/data/function.py

@@ -397,6 +397,67 @@ class Polynomial(np.polynomial.Polynomial, Function1D):
         return cls(dataset.value)
 
 
+class Combination(EqualityMixin):
+    """Combination of multiple functions with a user-defined operator
+
+    This class allows you to create a callable object which represents the
+    combination of other callable objects by way of a series of user-defined
+    operators connecting each of the callable objects.
+
+    Parameters
+    ----------
+    functions : Iterable of Callable
+        Functions to combine according to operations
+    operations : Iterable of numpy.ufunc
+        Operations to perform between functions; note that the standard order
+        of operations will not be followed, but can be simulated by
+        combinations of Combination objects. The operations parameter must have
+        a length one less than the number of functions.
+
+
+    Attributes
+    ----------
+    functions : Iterable of Callable
+        Functions to combine according to operations
+    operations : Iterable of numpy.ufunc
+        Operations to perform between functions; note that the standard order
+        of operations will not be followed, but can be simulated by
+        combinations of Combination objects. The operations parameter must have
+        a length one less than the number of functions.
+
+    """
+
+    def __init__(self, functions, operations):
+        self.functions = functions
+        self.operations = operations
+
+    def __call__(self, x):
+        ans = self.functions[0](x)
+        for i, operation in enumerate(self.operations):
+            ans = operation(ans, self.functions[i + 1](x))
+        return ans
+
+    @property
+    def functions(self):
+        return self._functions
+
+    @functions.setter
+    def functions(self, functions):
+        cv.check_type('functions', functions, Iterable, Callable)
+        self._functions = functions
+
+    @property
+    def operations(self):
+        return self._operations
+
+    @operations.setter
+    def operations(self, operations):
+        cv.check_type('operations', operations, Iterable, np.ufunc)
+        length = len(self.functions) - 1
+        cv.check_length('operations', operations, length, length_max=length)
+        self._operations = operations
+
+
 class Sum(EqualityMixin):
     """Sum of multiple functions.
 
@@ -432,6 +493,63 @@ class Sum(EqualityMixin):
         self._functions = functions
 
 
+class Regions1D(EqualityMixin):
+    """Piecewise composition of multiple functions.
+
+    This class allows you to create a callable object which is composed
+    of multiple other callable objects, each applying to a specific interval
+
+    Parameters
+    ----------
+    functions : Iterable of Callable
+        Functions which are to be combined in a piecewise fashion
+    breakpoints : Iterable of float
+        The values of the dependent variable that define the domain of
+        each function. The *i*th and *(i+1)*th values are the limits of the
+        domain of the *i*th function. Values must be monotonically increasing.
+
+    Attributes
+    ----------
+    functions : Iterable of Callable
+        Functions which are to be combined in a piecewise fashion
+    breakpoints : Iterable of float
+        The breakpoints between each function
+
+    """
+
+    def __init__(self, functions, breakpoints):
+        self.functions = functions
+        self.breakpoints = breakpoints
+
+    def __call__(self, x):
+        i = np.searchsorted(self.breakpoints, x)
+        if isinstance(x, Iterable):
+            ans = np.empty_like(x)
+            for j in range(len(i)):
+                ans[j] = self.functions[i[j]](x[j])
+            return ans
+        else:
+            return self.functions[i](x)
+
+    @property
+    def functions(self):
+        return self._functions
+
+    @property
+    def breakpoints(self):
+        return self._breakpoints
+
+    @functions.setter
+    def functions(self, functions):
+        cv.check_type('functions', functions, Iterable, Callable)
+        self._functions = functions
+
+    @breakpoints.setter
+    def breakpoints(self, breakpoints):
+        cv.check_iterable_type('breakpoints', breakpoints, Real)
+        self._breakpoints = breakpoints
+
+
 class ResonancesWithBackground(EqualityMixin):
     """Cross section in resolved resonance region.
 

openmc/data/library.py

@@ -22,6 +22,21 @@ class DataLibrary(EqualityMixin):
     def __init__(self):
         self.libraries = []
 
+    def get_by_material(self, value):
+        """Return the library dictionary containing a given material.
+
+        Returns
+        -------
+        library : dict or None
+            Dictionary summarizing cross section data from a single file;
+            the dictionary has keys 'path', 'type', and 'materials'.
+
+        """
+        for library in self.libraries:
+            if value in library['materials']:
+                return library
+        return None
+
     def register_file(self, filename):
         """Register a file with the data library.
 
@@ -78,3 +93,38 @@ class DataLibrary(EqualityMixin):
         tree = ET.ElementTree(root)
         tree.write(path, xml_declaration=True, encoding='utf-8',
                    method='xml')
+
+    @classmethod
+    def from_xml(cls, path):
+        """Read cross section data library from an XML file.
+
+        Parameters
+        ----------
+        path : str
+            Path to XML file to read.
+
+        Returns
+        -------
+        data : openmc.data.DataLibrary
+            Data library object initialized from the provided XML
+
+        """
+
+        data = cls()
+
+        tree = ET.parse(path)
+        root = tree.getroot()
+        if root.find('directory') is not None:
+            directory = root.find('directory').text
+        else:
+            directory = os.path.dirname(path)
+
+        for lib_element in root.findall('library'):
+            filename = os.path.join(directory, lib_element.attrib['path'])
+            filetype = lib_element.attrib['type']
+            materials = lib_element.attrib['materials'].split()
+            library = {'path': filename, 'type': filetype,
+                       'materials': materials}
+            data.libraries.append(library)
+
+        return data