added partly finished OperationConstraint

candidate_operations/candidate_generation.py

@@ -124,6 +124,48 @@ def random_pos(box):
         pos += vspan[i] * r[0, i]
     return pos
 
+class OperationConstraint():
+    """ Class used to enforce constraints on the positions of
+    atoms in mutation and crossover operations.
+
+    Parameters:
+
+    box: Box in which atoms are allowed to be placed. It should
+    have the form [] [p0, vspan] where 'p0' is the position of
+    the box corner and 'vspan' is a matrix containing the three
+    spanning vectors.
+
+    xlim: On the form [xmin, xmax], specifying, in the x-direction, 
+    the lower and upper limit of the region atoms can be moved 
+    within.
+
+    ylim, zlim: See xlim.
+    """
+    def __init__(self, box=None, xlim=None, ylim=None, zlim=None):
+        self.box = box
+        self.xlim = xlim
+        self.ylim = ylim
+        self.zlim = zlim
+
+    def check_if_valid(self, positions):
+        """ Returns whether positions are valid under the 
+        constraints or not.
+        """
+        if self.box is not None:
+            pass
+        if self.x is not None:
+            if (np.any(positions[:,0] < self.xlim[0]) or 
+                    np.any(positions[:,0] > self.xlim[1])):
+                return False
+        if self.y is not None:
+            if (np.any(positions[:,1] < self.ylim[0]) or 
+                    np.any(positions[:,1] > self.ylim[1])):
+                return False
+        if self.z is not None:
+            if (np.any(positions[:,2] < self.zlim[0]) or 
+                    np.any(positions[:,2] > self.zlim[1])):
+                return False
+
 class StartGenerator(CandidateGenerator):
     """ Class used to generate random initial candidates.
     The candidates are generated by iteratively adding in