refactored l-system code

_sources/Python/Strings/LSystems.rst

@@ -128,34 +128,29 @@ above.
         """Apply rules to an individual letter, and return the result."""
         # Rule 1
         if letter == 'A':
-            new_string = 'B'
+            return 'B'
 
         # Rule 2
         elif letter == 'B':
-            new_string = 'AB'
+            return 'AB'
 
         # no rules apply so keep the character
         else:
-            new_string = letter
-
-        return new_string
+            return letter
 
     def process_string(original_string):
         """Apply rules to a string, one letter at a time, and return the result."""
         tranformed_string = ""
         for letter in original_string:
             tranformed_string = tranformed_string + apply_rules(letter)
-
         return tranformed_string
 
     def create_l_system(number_of_iterations, axiom):
         """Begin with an axiom, and apply rules to the original axiom string number_of_iterations times, then return the result."""
-        start_string = axiom
+        new_string = axiom
         for counter in range(number_of_iterations):
-            end_string = process_string(start_string)
-            start_string = end_string
-
-        return end_string
+            new_string = process_string(new_string)
+        return new_string
 
     print(create_l_system(4, "A"))
 
@@ -208,13 +203,12 @@ Here is the ``apply_rules`` function for this L-system.
         """Apply rules to an individual letter, and return the result."""
         # Rule 1
         if letter == 'F':
-            new_string = 'F-F++F-F'
+            return 'F-F++F-F'
 
         # no rules apply so keep the character
         else:
-            new_string = letter
+            return letter
 
-        return new_string
 
 Pretty simple so far.  As you can imagine this string will get pretty long
 with a few applications of the rules.  You might try to expand the string a
@@ -259,30 +253,25 @@ Here is the complete program, which combines generating the L-System string, and
         """Apply rules to an individual letter, and return the result."""
         # Rule 1
         if letter == 'F':
-            new_string = 'F-F++F-F'
+            return 'F-F++F-F'
 
         # no rules apply so keep the character
         else:
-            new_string = letter
-
-        return new_string
+            return letter
 
     def process_string(original_string):
         """Apply rules to a string, one letter at a time, and return the result."""
         tranformed_string = ""
         for letter in original_string:
             tranformed_string = tranformed_string + apply_rules(letter)
-
         return tranformed_string
 
     def create_l_system(number_of_iterations, axiom):
         """Begin with an axiom, and apply rules to the original axiom string number_of_iterations times, then return the result."""
-        start_string = axiom
+        new_string = axiom
         for counter in range(number_of_iterations):
-            end_string = process_string(start_string)
-            start_string = end_string
-
-        return end_string
+            new_string = process_string(new_string)
+        return new_string
 
     def draw_l_system(some_turtle, instructions, angle, distance):
         """Draw with some_turtle, interpreting each letter in the instructions passed in."""