Changeset 4026380 in sasview for DataLoader/invariant.py

Timestamp:

Nov 14, 2009 10:33:21 AM (15 years ago)

Author:

Mathieu Doucet <doucetm@…>

Branches:

master, ESS_GUI, ESS_GUI_Docs, ESS_GUI_batch_fitting, ESS_GUI_bumps_abstraction, ESS_GUI_iss1116, ESS_GUI_iss879, ESS_GUI_iss959, ESS_GUI_opencl, ESS_GUI_ordering, ESS_GUI_sync_sascalc, costrafo411, magnetic_scatt, release-4.1.1, release-4.1.2, release-4.2.2, release_4.0.1, ticket-1009, ticket-1094-headless, ticket-1242-2d-resolution, ticket-1243, ticket-1249, ticket885, unittest-saveload

Children:

fd6b789

Parents:

c13b8cc

Message:

dataloader: improved invariant

File:

• DataLoader/invariant.py (modified) (9 diffs)

DataLoader/invariant.py

@@ -14 +14 @@
         @note: The data boundaries are assumed as infinite range. 
     """
-    def __init__(self, data,contrast=None, pConst=None):
+    def __init__(self, data):
         """
             Initialize variables
@@ -21 +21 @@
             @param pConst: Porod Constant of type float
         """
-        self.q_star = self.getQstar(data= data)
-        self.volume = self._getVolFrac(contrast= contrast)
-        self.surface= self._getSurface(pConst= pConst)
+        ## Invariant
+        self.q_star = self._get_q_star(data= data)
         
-    def __call__(self, contrast, pConst):
-        """
-            @precondition: self.q_star has already been computed
-        """
-        self.volume = self._getVolFrac(contrast= contrast)
-        self.surface = self._getSurface(pConst= pConst)
-        
-        return self
-        
-    def getQstar(self, data):
+    def _get_q_star(self, data):
         """
             @param data: data of type Data1D
@@ -42 +32 @@
             #Process only data that inherited from DataLoader.Data_info.Data1D
             raise ValueError,"Data must be of type DataLoader.Data1D"
-        if data.dxl == None:
-            return self._getQStarUnsmear(data= data)
+        
+        # Check whether we have slit smearing information
+        if data.is_slit_smeared():
+            return self._get_qstar_unsmeared(data= data)
         else:
-            return self._getQStarSmear(data= data)
+            return self._get_qstar_smeared(data= data)
     
             
             
-    def _getQStarUnsmear(self, data):
+    def _get_qstar_unsmeared(self, data):
         """
             @param data: data of type Data1D
@@ -86 +78 @@
             
                
-    def _getQStarSmear(self, data):
+    def _get_qstar_smeared(self, data):
         """
             @param data: data of type Data1D
-            Compute invariant with smearing info
+            Compute invariant with slit smearing info
             q_star= x0*dxl *y0 *dx0 + x1*dxl *y1 *dx1 + ..+ xn*dxl *yn *dxn 
             where n= infinity
@@ -125 +117 @@
                 return sum
         
-    def _getVolFrac(self,contrast):
+    def get_volume_fraction(self, contrast):
         """
             Compute volume fraction is given by:
@@ -137 +129 @@
                 q_star unit  1/A^(3)*1/cm
                 
-            the result returned will be 0<= volume <= 1 or None
+            the result returned will be 0<= volume <= 1
             
             @param contrast: contrast value provides by the user of type float
-            @return None : if the invariant Calculator does not a computed
-            q_star already  stored
+            @return: volume fraction
             @note: volume fraction must have no unit
         """
-        if contrast ==None:
-            #No contrast value is provided for calculation then no calculation
-            return 
         if contrast < 0:
             raise ValueError, "contrast must be greater than zero"  
         
         if self.q_star ==None:
-            return  
+            raise RuntimeError, "Q_star is not defined"
         
         if self.q_star < 0:
-            raise ValueError, "invariant must be greater than zero"
+            raise ValueError, "invariant must be greater than zero. Q_star=%g" % self.q_star
        
         #compute intermediate constant
@@ -161 +149 @@
         discrim= 1 - 4*k
         if discrim < 0:
-            return 
+            raise RuntimeError, "could not compute the volume fraction: negative discriminant"
         elif discrim ==0:
             volume = 1/2
@@ -169 +157 @@
             volume1 = 0.5 *(1 - math.sqrt(discrim))
             volume2 = 0.5 *(1 + math.sqrt(discrim))
-            print "volume1",volume1
-            print "volume2",volume2
            
             if 0<= volume1 and volume1 <= 1:
@@ -176 +162 @@
             elif 0<= volume2 and volume2<= 1: 
                 return volume2 
-            return 
+            raise RuntimeError, "could not compute the volume fraction: inconsistent results"
     
-    def _getSurface(self, pConst, volume=None):
+    def get_surface(self, contrast, porod_const):
         """
             Compute the surface given by:
                 surface = (2*pi *volume(1- volume)*pConst)/ q_star
-            @param volume : volume previously calculated
-            @return None: if volume used for computation equal None
+                
+            @param contrast: contrast value provides by the user of type float
+            @param porod_const: Porod constant 
+            @return: specific surface
         """
-        #check if the user provides a value for volume
-        if volume != None:
-            self.volume = float(volume)
+        # Compute the volume
+        volume = self.get_volume_fraction(contrast)
         
-        #return None if volume or q_star is not computed
-        if self.q_star ==None or self.volume == None:
-            return 
+        # Check whether we have Q star
+        if self.q_star ==None:
+            raise RuntimeError, "Q_star is not defined"
+        
         if self.q_star ==0:
-            raise ZeroDivisionError, "invariant must be greater than zero"
+            raise ValueError, "invariant must be greater than zero. Q_star=%g" % self.q_star
         
-        return 2*math.pi*self.volume*(1- self.volume)*float(pConst)/self.q_star
+        return 2*math.pi*volume*(1-volume)*float(porod_const)/self.q_star