[Tutor] manipulating data

[Bryan Fodness]

Using the algorithm below, I get:

     Traceback (most recent call last):
       File "C:\Users\bryan\Documents\Yennes Medical
Physics\mlcShape\findvalue.py", line 49, in <module>
         file.next()
     TypeError: descriptor 'next' of 'file' object needs an argument

And, it is true that I am trying to build a list and not overwrite the value.

On Nov 12, 2007 5:22 PM, ALAN GAULD <alan.gauld at btinternet.com> wrote:
> Brian,
>
> >     if line.split()[0] == 'Field':
> >        field = int(line.split()[-1])
> >
> > IndexError: list index out of range
>
>
> You have blank lines in the file, when you try to call split
> on an empty string you get an empty list so trying to
> index any element will result in an Index error.
>
> That's why I suggested using exceptions, testing for
> every possible error condition could take a long time
> and be error prone. Unfortunately I guessed the wrong
> error code and didn't realise you had some dross to
> wade through first... so its a wee bit more complex.
>
> Personally I'd use a flag to detect when field had
> been found and set - ie set field to None and then
> test for that changing, then test for Leaf as you do.
>
> So I think your algorithm should be
>
> for line in file
>    if 'Field' in line:
>       field = int(line.split()[-1])
>    elif 'Leaf' in line:
>       fields[field] = line.split()[-1]
>    else: file.next()
>
> But I think there's another problem in that you are
> then overwriting the value of Leaf when I think you
> are trying to build a list? I'm not 100% sure what
> you are aiming for but hopefully its some help!
>
> Alan G.
>
>
>
>