Enumerating ordered expat attributes with tuplets?

[andy_westken at hotmail.com]

On Sep 11, 4:48 pm, Manuel Ebert <maeb... at uos.de> wrote:
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> Ah, well. Don't know whether it meets your aesthetic standards, but:
>  >>> my_list = ['tree', 'hug', 'flower', 'hug', 'bear', 'run']
>  >>> my_list[0:len(a):2]
> ['tree', 'flower', 'bear']
>  >>> my_list[1:len(a):2]
> ['hug', 'hug', 'run']
>
> and hence
>
>  >>> zip(my_list[0:len(a):2], my_list[1:len(a):2])
> [('tree', 'hug'), ('flower', 'hug'), ('bear', 'run')]
>
> and furthermore
>
>  >>> for a, b in zip(my_list[0:len(a):2], my_list[1:len(a):2]):
> ...     print a, b
> ...
> tree hug
> flower hug
> bear run
>
> or the slightly less obfuscated:
>
>  >>> for index in range(0, len(my_list), 2):
> ...     print my_list[index], my_list[index + 1]
> ...    
> tree hug
> flower hug
> bear run
>
> On Sep 11, 2008, at 5:19 PM, andy_west... at hotmail.com wrote:
>
>
>
>
>
> > On Sep 11, 4:04 pm, Manuel Ebert <maeb... at uos.de> wrote:
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> >> Hi Andy,
>
> >> by the looks of it I'd say that the problem is that the second
> >> parameter you passed to start_element is not a dictionary at all (the
> >> clue is in the "AttributeError: 'LIST' object" ...).
>
> >>  >>> d = ['tree', 'house']
> >>  >>> start_element("Thing", d)
> >> Thing :
> >> AttributeError: 'list' object has no attribute 'items'
> >>  >>> d = {'tree': 'hug', 'flower' : 'eat'}
> >>  >>> start_element("Thing", d)
> >> Thing :   flower="eat"  tree="hug"
>
> >> Manuel
>
> >> On Sep 11, 2008, at 4:21 PM, andy_west... at hotmail.com wrote:
>
> >>> Hi
>
> >>> I'm new to Python and trying to pick up good, idiomatic usage right
> >>> from the offset.
>
> >>> As I was familiar with Expat from C++ (directly and via expatpp) I'm
> >>> trying to write a little script - using xml.parsers.expat - to  
> >>> search
> >>> and replace XML attribute values.
>
> >>> As I want the attributes to stay in order when the file is  
> >>> written out
> >>> (so I can check my results with a diff tool) I've set the parser's
> >>> ordered_attributes attribute. But this has stopped the for loop
> >>> working with the tuplets.
>
> >>> The relevant bit of code in my little test, using the default
> >>> Dictionary for the attributes, is:
>
> >>> def start_element(name, attrs):
> >>>     print "%s : " % name,
> >>>     for (a,b) in attrs.items():
> >>>         print " %s=\"%s\"" % (a,b),
>
> >>> But when I set ordered_attributes, first it doesn't like the items()
>
> >>>     AttributeError: 'list' object has no attribute 'items'
>
> >>> And then it doesn't like the tuple
>
> >>>     ValueError: too many values to unpack
>
> >>> Do I have keep track of where I am (name, value, name, value, ...)
>
> >>> Or is there a way I can solve the problem with a tuple?
>
> >>> Thanks, Andy
> >>> --
> >>>http://mail.python.org/mailman/listinfo/python-list
>
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> > Sorry!
>
> > I forgot to mention that when you set the parser's ordered_attributes
> > attribute, it sends the "attrs" to start_element as a list, not a
> > dictionary, in the order name, value, name, value, ...
>
> > Andy
> > --
> >http://mail.python.org/mailman/listinfo/python-list
>
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Thanks!

Regarding aesthetics - I don't need it to look pretty: I want it to be
understandable to people who know Python (?), and then as efficient as
possible.

Of the two examples about (the 'zip' solution and the 'range'
solution), is there much difference in performance?

Andy