Merge branch 'patch-1' of https://github.com/danshorstein/python-guide

docs/writing/structure.rst

@@ -787,6 +787,11 @@ full string is needed. One thing to notice, however, is that list
 comprehensions are better and faster than constructing a list in a loop
 with calls to ``append()``. 
 
+One other option is using the map function, which can 'map' a function
+('str') to an iterable ('range(20)'). This results in a map object,
+which you can then ('join') together just like the other examples.
+The map function can be even faster than a list comprehension in some cases.
+
 **Bad**
 
 .. code-block:: python
@@ -807,7 +812,7 @@ with calls to ``append()``.
       nums.append(str(n))
     print "".join(nums)  # much more efficient
 
-**Best**
+**Better**
 
 .. code-block:: python
 
@@ -815,6 +820,14 @@ with calls to ``append()``.
     nums = [str(n) for n in range(20)]
     print "".join(nums)
     
+**Best**
+
+.. code-block:: python
+
+    # create a concatenated string from 0 to 19 (e.g. "012..1819")
+    nums = map(str, range(20))
+    print "".join(nums) 
+
 One final thing to mention about strings is that using ``join()`` is not always
 best. In the instances where you are creating a new string from a pre-determined
 number of strings, using the addition operator is actually faster, but in cases