Changing SIfloat to only convert last character of the string

pykat/SIfloat.py

 import os
 import re
+import pykat.exceptions as pkex
 
-#staticmethod
-def SIfloat(value):
-    if value==None: 
-        return value
-    if type(value)==list:
-        return [convertToFloat(s) for s in value]
-    else:
-        return convertToFloat(value)
-    
-def convertToFloat(value):
 __suffix = {'y': 'e-24',  # yocto
             'z': 'e-21',  # zepto
             'a': 'e-18',  # atto
@@ -28,9 +19,35 @@ def convertToFloat(value):
             'P': 'e15'   # peta
             }
             
-    value = str(value)
+def SIfloat(value):
+    if value==None: 
+        return value
+    
+    if type(value)==list:
+        return [convertToFloat(s) for s in value]
+    else:
+        return convertToFloat(value)
+    
+def convertToFloat(value):
+    
+    try:
+        # first just try and convert the value
+        return float(value)
         
-    for i, j in __suffix.iteritems():
-        value=value.replace(i, str(j))
+    except ValueError as ex:
+        # Catch any casting exeception
+        value = value.strip()
+        
+        # only the last value can be an SI scaling letter 
+        last = value[-1]
+
+        if last in __suffix:
+            # remove last character and append the SI scaling
+            value = value[0:-1] + __suffix[last]
+        else:
+            raise pkex.BasePyKatException("Could not convert SI scaling in '{0}' to a float".format(value))
         
+        try:   
             return float(value)
+        except ValueError as ex:
+            raise pkex.BasePyKatException("Unable to convert '{0}' into a float".format(value))