Dictionary/Hash question

[Sick Monkey]

I have never seen this "with open(fname,'r') as finput:"

It is actually throwing an error .  Do I have to import a special library to
use this?

 File "dictNew.py", line 23
    with open(fname,'r') as finput:
            ^
SyntaxError: invalid syntax
On 2/6/07, Gabriel Genellina <gagsl-py at yahoo.com.ar> wrote:
>
> En Tue, 06 Feb 2007 20:31:17 -0300, Sick Monkey <sickcodemonkey at gmail.com>
> escribió:
>
> > Even though I am starting to get the hang of Python, I continue to find
> > myself finding problems that I cannot solve.
> > I have never used dictionaries before and I feel that they really help
> > improve efficiency when trying to analyze huge amounts of data (rather
> > than
> > having nested loops).
>
> You are right, a list is not the right data structure in your case.
> But a dictionary is a mapping from keys to values, and you have no values
> to store.
> In this case one should use a set: like a list, but without ordering, and
> no duplicated elements.
> Also, it's not necesary to read all lines at once, you can process both
> files line by line. And since reading both files appears to be the same
> thing, you can make a function:
>
> def mailsfromfile(fname):
>    result = set()
>    with open(fname,'r') as finput:
>      for line in finput:
>        mails = some_regular_expression.findall(line)
>        if mails:
>          result.update(mails)
>    return result
>
> mails1 = mailsfromfile(f1name)
> mails2 = mailsfromfile(f2name)
>
> for mail in mails1 & mails2: # & = set intersection, mails present on both
> files
>    # write mail to output file
>
> --
> Gabriel Genellina
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>
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