Core Python Programming (2nd Edition)

$ python oddnogen.py
[39, 77, 39, 71, 1]
$ python oddnogen.py
[23, 39, 9, 1, 63, 91]
$ python oddnogen.py
[41, 85, 93, 53, 3]
Refactoring Pass 1
We notice on second glance that odd() is simple enough to be replaced by a lambda expression:
from random import randint
allNums = []
for eachNum in range(9):
allNums.append(randint(1, 99))
print filter(lambda n: n%2, allNums)
Refactoring Pass 2
We have already mentioned how list comprehensions can be a suitable replacement for filter() so here
it is:
from random import randint
allNums = []
for eachNum in range(9):
allNums.append(randint(1, 99))
print [n for n in allNums if n%2]
Refactoring Pass 3
We can further simplify our code by integrating another list comprehension to put together our final list.
As you can see below, because of the flexible syntax of list comps, there is no longer a need for
intermediate variables. (To make things fit, we import randint() with a shorter name into our code.)
from random import randint as ri
print [n for n in [ri(1,99) for i in range(9)] if n%2]
Although longer than it should be, the line of code making up the core part of this example is not as
obfuscated as one might think.
map( )
The map() built-in function is similar to filter() in that it can process a sequence through a function.
However, unlike filter(), map() "maps" the function call to each sequence item and returns a list