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Insert missing keys using defaultdict

Gnarlodious

3/11/2010 4:03:00 PM

I am trying to grok this documentation but need help:
http://docs.python.org/library/collections.html#defaultdic...

In a perfect world the dict looks like this:
plistDict={'Style':'ExternalURL', 'Ref':'http://Gnarlodious...,
'Tip':'Opens in a new window', 'Text':'Gnarlodious.com'}

Let's say I want to prep a dict from a plist to insert the values into
an HTML link string:
"<a class='%(Style)s' href='%(Ref)s' title='%(Tip)s'>%(Text)s</a>" %
plistDict

However, in this imperfect world the dict might look like this:
plistDict={'Ref':'http://Gnarlodious..., 'Text':'Gnarlodious.com'}

which would error:
KeyError: 'Style'

So using defaultdict:
from collections import defaultdict

How do create a dict assigning every missing key with a default
string?

-- Gnarlie
2 Answers

George Sakkis

3/11/2010 4:21:00 PM

0

On Mar 11, 5:02 pm, Gnarlodious <gnarlodi...@gmail.com> wrote:

> I am trying to grok this documentation but need help:http://docs.python.org/library/collections.html#defaultdic...
>
> In a perfect world the dict looks like this:
> plistDict={'Style':'ExternalURL', 'Ref':'http://Gnarlodious...,
> 'Tip':'Opens in a new window', 'Text':'Gnarlodious.com'}
>
> Let's say I want to prep a dict from a plist to insert the values into
> an HTML link string:
> "<a class='%(Style)s' href='%(Ref)s' title='%(Tip)s'>%(Text)s</a>" %
> plistDict
>
> However, in this imperfect world the dict might look like this:
> plistDict={'Ref':'http://Gnarlodious..., 'Text':'Gnarlodious.com'}
>
> which would error:
> KeyError: 'Style'
>
> So using defaultdict:
> from collections import defaultdict
>
> How do create a dict assigning every missing key with a default
> string?

"<a class='%(Style)s' href='%(Ref)s' title='%(Tip)s'>%(Text)s</a>" %
defaultdict(lambda:'_MISSING_', plistDict)

HTH,
George

Gnarlodious

3/11/2010 4:27:00 PM

0

On Mar 11, 9:20 am, George Sakkis wrote:

> > How do create a dict assigning every missing key with a default
> > string?
>
> "<a class='%(Style)s' href='%(Ref)s' title='%(Tip)s'>%(Text)s</a>" %
> defaultdict(lambda:'_MISSING_', plistDict)

Brilliant, I love Python.

-- Gnarlie