Index: src/sas/sasgui/perspectives/pr/inversion_panel.py
===================================================================
--- src/sas/sasgui/perspectives/pr/inversion_panel.py	(revision c1d5aeab1ee75d2bf50cd73195f34c011918657d)
+++ src/sas/sasgui/perspectives/pr/inversion_panel.py	(revision 235f514ba93b57fa63e44309f182acef0b98bb55)
@@ -920,5 +920,5 @@
         if flag:
             dataset = self.plot_data.GetValue()
-            if dataset == None or len(dataset.strip()) == 0:
+            if dataset is None or len(dataset.strip()) == 0:
                 message = "No data to invert. Select a data set before"
                 message += " proceeding with P(r) inversion."
Index: src/sas/sasgui/perspectives/pr/pr.py
===================================================================
--- src/sas/sasgui/perspectives/pr/pr.py	(revision 959eb0181ad06828a748f04512f953aad5b31659)
+++ src/sas/sasgui/perspectives/pr/pr.py	(revision 235f514ba93b57fa63e44309f182acef0b98bb55)
@@ -291,5 +291,5 @@
         """
         qtemp = pr.x
-        if not q == None:
+        if not q is None:
             qtemp = q
 
@@ -303,7 +303,7 @@
 
         # Check for user min/max
-        if not pr.q_min == None:
+        if not pr.q_min is None:
             minq = pr.q_min
-        if not pr.q_max == None:
+        if not pr.q_max is None:
             maxq = pr.q_max
 
@@ -393,5 +393,5 @@
 
         for i in range(len(x)):
-            if cov2 == None:
+            if cov2 is None:
                 value = pr.pr(out, x[i])
             else:
@@ -412,5 +412,5 @@
             dy = dy / pmax
 
-        if cov2 == None:
+        if cov2 is None:
             new_plot = Data1D(x, y)
             new_plot.symbol = GUIFRAME_ID.CURVE_SYMBOL_NUM
@@ -487,5 +487,5 @@
         scale = None
         min_err = 0.0
-        if not path == None:
+        if not path is None:
             input_f = open(path, 'r')
             buff = input_f.read()
@@ -499,5 +499,5 @@
                         err = float(toks[2])
                     else:
-                        if scale == None:
+                        if scale is None:
                             scale = 0.05 * math.sqrt(y)
                             #scale = 0.05/math.sqrt(y)
@@ -512,5 +512,5 @@
                     logger.error(sys.exc_value)
 
-        if not scale == None:
+        if not scale is None:
             message = "The loaded file had no error bars, statistical errors are assumed."
             wx.PostEvent(self.parent, StatusEvent(status=message))
@@ -537,5 +537,5 @@
 
         data_started = False
-        if not path == None:
+        if not path is None:
             input_f = open(path, 'r')
             buff = input_f.read()
@@ -550,5 +550,5 @@
                             err = float(toks[2])
                         else:
-                            if scale == None:
+                            if scale is None:
                                 scale = 0.05 * math.sqrt(y)
                                 #scale = 0.05/math.sqrt(y)
@@ -565,5 +565,5 @@
                     data_started = True
 
-        if not scale == None:
+        if not scale is None:
             message = "The loaded file had no error bars, statistical errors are assumed."
             wx.PostEvent(self.parent, StatusEvent(status=message))
@@ -761,5 +761,5 @@
         self.elapsed = elapsed
         self.control_panel.alpha_estimate = alpha
-        if not message == None:
+        if not message is None:
             wx.PostEvent(self.parent, StatusEvent(status=str(message)))
         self.perform_estimateNT()
@@ -779,5 +779,5 @@
         self.control_panel.nterms_estimate = nterms
         self.control_panel.alpha_estimate = alpha
-        if not message == None:
+        if not message is None:
             wx.PostEvent(self.parent, StatusEvent(status=str(message)))
 
@@ -858,5 +858,5 @@
 
         # Make a plot of I(q) data
-        if self.pr.err == None:
+        if self.pr.err is None:
             new_plot = Data1D(self.pr.x, self.pr.y)
             new_plot.symbol = GUIFRAME_ID.CURVE_SYMBOL_NUM
@@ -921,5 +921,5 @@
         try:
             pr = self._create_plot_pr()
-            if not pr == None:
+            if not pr is None:
                 self.pr = pr
                 self.perform_inversion()
@@ -944,5 +944,5 @@
         try:
             pr = self._create_plot_pr()
-            if not pr == None:
+            if not pr is None:
                 self.pr = pr
                 self.perform_estimate()
@@ -983,5 +983,5 @@
         err = self.current_plottable.dy
         all_zeros = True
-        if err == None:
+        if err is None:
             err = np.zeros(len(pr.y))
         else:
@@ -995,5 +995,5 @@
             for i in range(len(pr.y)):
                 # Scale the error so that we can fit over several decades of Q
-                if scale == None:
+                if scale is None:
                     scale = 0.05 * math.sqrt(pr.y[i])
                     min_err = 0.01 * pr.y[i]
@@ -1024,5 +1024,5 @@
         try:
             pr = self._create_file_pr(data)
-            if not pr == None:
+            if not pr is None:
                 self.pr = pr
                 self.perform_inversion()
@@ -1090,5 +1090,5 @@
         # If we have not errors, add statistical errors
         if y is not None:
-            if err == None or np.all(err) == 0:
+            if err is None or np.all(err) == 0:
                 err = np.zeros(len(y))
                 scale = None
@@ -1096,5 +1096,5 @@
                 for i in range(len(y)):
                     # Scale the error so that we can fit over several decades of Q
-                    if scale == None:
+                    if scale is None:
                         scale = 0.05 * math.sqrt(y[i])
                         min_err = 0.01 * y[i]
Index: src/sas/sasgui/perspectives/pr/pr_thread.py
===================================================================
--- src/sas/sasgui/perspectives/pr/pr_thread.py	(revision 959eb0181ad06828a748f04512f953aad5b31659)
+++ src/sas/sasgui/perspectives/pr/pr_thread.py	(revision 235f514ba93b57fa63e44309f182acef0b98bb55)
@@ -42,5 +42,5 @@
             pass
         except:
-            if not self.error_func == None:
+            if not self.error_func is None:
                 self.error_func("CalcPr.compute: %s" % sys.exc_value)
 
@@ -70,5 +70,5 @@
             pass
         except:
-            if not self.error_func == None:
+            if not self.error_func is None:
                 self.error_func("EstimatePr.compute: %s" % sys.exc_value)
 
@@ -110,4 +110,4 @@
             pass
         except:
-            if not self.error_func == None:
+            if not self.error_func is None:
                 self.error_func("EstimatePr2.compute: %s" % sys.exc_value)
