I am out of trial and error again Lists
denismfmcmahon at gmail.com
Thu Oct 23 00:43:14 CEST 2014
On Wed, 22 Oct 2014 16:30:37 -0400, Seymore4Head wrote:
> def nametonumber(name):
> for x,y in enumerate (name):
> print (lst)
> return (lst)
> print (nametonumber(a))#18004382427837
> The syntax for when to use a () and when to use  still throws me a
> For now, I am trying to end up with a list that has each character in
> "a" as a single item.
> I get:
> None None
First of all, an empty list is created with:
emptylist = 
x = [""]
creates a list containing one element, that element being an empty
string. Not the same thing!
Did you try stepping through your code line by line in the interpreter to
see what happened at each step?
note that append is a method of a list object, it has no return value,
the original list is modified in place.
>>> l = ["a","b","c"] # declare a list
>>> l.append( "d" ) # use the append method
>>> l # show the list
['a', 'b', 'c', 'd']
So your line:
lst = lst.append(y)
Finally, did you really intend to pass a single element list into the
function, or did you intend to pass a string into the function?
There is a difference between:
which creates a single element list, the one element is the string "1-800-
which creates a string variable with the value "1-800-getcharter"
when you pass a list containing a string to your function, enumerate will
look at each list element, so if your list contains one string, enumerate
will return the pair 0, the_string, so the string gets appended to your
empty list as a single item.
The code I think you wanted to write is as follows:
for x,y in enumerate(name):
print ( nametonumber(a) )
I suggests that you study very carefully the differences between this and
your original code until you understand the reason and effect of every
difference, as only by doing so will you discover the misconceptions
which you seem to be operating under, and until you can get some of those
straightened out, you're not going to make a lot of progress.
Try running the original code and my suggested alternative line by line
in the interpreter, and examining the state of relevant variables after
each line of execution.
Here's a code file with both your original code and my modified code with
comprehensive print statements inserted for debugging. By referencing the
debugging statements back to the code, you should be able to determine
exactly where in your original code the value of "none" comes from.
### code starts
print ( "original code" )
print ("a) name =", name)
print ( "b) lst = ", lst )
for x,y in enumerate (name):
print ( "c) x = ", x, "; y = ", y, "; lst = ", lst )
print ( "d) lst = ", lst )
print ( "e) a = ", a )
print ( "modified code" )
print ("f) name =", name)
print ( "g) lst = ", lst )
for x,y in enumerate(name):
print ( "h) x = ", x, "; y = ", y, "; lst = ", lst )
print ( "i) lst = ", lst )
print ( "j) a = ", a )
print ( nametonumber2(a) )
### code ends
If you run the above code exactly as it is, you should see in the output
how the enumeration reacts according to the different data it is given to
enumerate, and also where lst is assigned the value none.
As I said above, getting your head round why this is happening is
essential, and I really do suggest that you slow down and try and
understand these basic concepts, because at the moment it seems you are
striving to attempt more and more complicated things without
understanding the basics upon which they are constructed, and like many
other similar newsgroups, it's been my experience in the past that there
is limited tolerance here for people who repeatedly make the same basic
errors without learning from them.
Denis McMahon, denismfmcmahon at gmail.com
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