Syntax for extracting multiple items from a dictionary

[Peter Hansen]

Dave Merrill wrote:
> "anton muhin" wrote:
>>Or dict((key, row[key]) for key in cols).
> 
> I'm on Py 2.3.3, and neither of these appear to work. 

You're probably getting the error shown.  Try the change in
the line following it instead.

Python 2.3.4 (#53, May 25 2004, 21:17:02) [MSC v.1200 32 bit (Intel)]
 >>> row = {'fname': 'Frank', 'lname': 'Jones', 'city': 'Hoboken', 
'state': 'Alaska'}
 >>> cols = ['city', 'state']
 >>> dict((key, row[key]) for key in cols)
   File "<stdin>", line 1
     dict((key, row[key]) for key in cols)
                            ^
SyntaxError: invalid syntax
 >>> dict([(key, row[key]) for key in cols])
{'city': 'Hoboken', 'state': 'Alaska'}


> I can't see anything in the 2.4 release notes that point to where this would
> have changed.

See http://www.python.org/2.4/highlights.html and search for
"generator expressions".

-Peter