Changeset 1927

Timestamp:

Oct 14, 2005, 4:14:19 PM (19 years ago)

Author:

ole

Message:

Improved expression parser for apply_expression_to_dictionary()

Files:

• inundation/pyvolution/data_manager.py (modified) (1 diff)
• inundation/pyvolution/test_util.py (modified) (1 diff)
• inundation/pyvolution/util.py (modified) (1 diff)
• tools/pytools/misc.py (modified) (2 diffs)

inundation/pyvolution/data_manager.py

@@ -1322 +1322 @@
     quantity_dict = {}
     for name in fid.variables.keys():
-
-        if name not in ['x', 'y', 'volumes', 'time']:
-            quantity_dict[name] = fid.variables[name][:]
+        quantity_dict[name] = fid.variables[name][:]
 
     #print quantity_dict     

inundation/pyvolution/test_util.py

@@ -1012 +1012 @@
         
 
+    def test_multiple_replace(self):
+        """Hard test that checks a true word-by-word simultaneous replace
+        """
+        
+        D = {'x': 'xi', 'y': 'eta', 'xi':'lam'}
+        exp = '3*x+y + xi'
+        
+        new = multiple_replace(exp, D)
+        
+        assert new == '3*xi+eta + lam'
+                          
 
 

inundation/pyvolution/util.py

@@ -460 +460 @@
 
 
-
-
-
-def apply_expression_to_dictionary(expression, _):
-    """Apply arbitrary expression to values of dictionary _
-
-    expression: Arbitrary, e.g. arithmetric, expression relating keys
-                from dictionary _. A key must not be the single character '_'
-
-    _: Dictionary of variable names used in expression and their
-       corresponding values. The dictinary name is chosen as the
-       inconspicuous symbol _ in order to avoid single letter variable
-       to inabvertently substitute parts of the dictionary name
-    
+def multiple_replace(text, dictionary):
+    """Multiple replace of words in text
+
+    text:       String to be modified
+    dictionary: Mapping of words that are to be substituted
+
+    Python Cookbook 3.14 page 88 and page 90
+    """
+
+    import re
+    
+    #Create a regular expression from all of the dictionary keys
+    #matching only entire words
+    regex = re.compile(r'\b'+ \
+                       r'\b|\b'.join(map(re.escape, dictionary.keys()))+ \
+                       r'\b' )
+
+    #For each match, lookup the corresponding value in the dictionary
+    return regex.sub(lambda match: dictionary[match.group(0)], text)
+
+
+
+
+def apply_expression_to_dictionary(expression, dictionary):#dictionary):
+    """Apply arbitrary expression to values of dictionary
 
     Given an expression in terms of the keys, replace key by the
     corresponding values and evaluate.
-
-    Values in dictionary must support operators given in expression
-    e.g. by overloading
-    """
-
-    
+   
+
+    expression: Arbitrary, e.g. arithmetric, expression relating keys
+                from dictionary. 
+
+    dictionary: Mapping between symbols in expression and objects that
+                will be evaluated by expression.
+                Values in dictionary must support operators given in
+                expression e.g. by overloading                
+    """
+
     import types
     import re
 
     assert isinstance(expression, basestring)
-    assert type(_) == types.DictType
-
-
-    #FIXME: Varibles may substitute into other variables e.g. x into xmomentum.
-
-    #words = re.compile("^.*?\\b([A-Za-z'-]+)\\b(.*)$")
-    #words = re.compile("[A-Za-z]")
-    #print expression
-    #res = words.search(expression)
-    #for 
-    #print 'Res ', res.group(0)
-    #print 'Res ', res.group(1)
-    #tokens =
-
-    #Replace key names with values
-    for key in _.keys():
-        msg = 'Key must not be the single character "_"'
-        assert key != '_', msg
-        expression = expression.replace(key,
-                                        '_["%s"]' %key)
-
+    assert type(dictionary) == types.DictType
+
+    #Convert dictionary values to textual representations suitable for eval
+    D = {}
+    for key in dictionary:
+        D[key] = 'dictionary["%s"]' %key
+
+    #Perform substitution of variables    
+    expression = multiple_replace(expression, D)
 
     #Evaluate and return

tools/pytools/misc.py

@@ -1 +1 @@
       
+def multiple_replace(dictionary, text):
+    """Multiple replace
+
+    Python Cookbook 3.14 page 88 and page 90
+    """
+
+    import re
+    
+    #Create a regular expression from all of the dictionary keys
+    #matching only entire words
+    #regex = re.compile("|".join(map(re.escape, dictionary.keys())))
+    regex = re.compile(r'\b'+ \
+                       r'\b|\b'.join(map(re.escape, dictionary.keys()))+ \
+                       r'\b' )
+
+    #For each match, lookup the corresponding value in the dictionary
+    return regex.sub(lambda match: dictionary[match.group(0)], text)
+
+
 def merge_dictionaries(D1,D2):
     """merge_dictionaries(D1,D2)
@@ -19 +38 @@
     return D1
 
+
+