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comp.lang.python

Re: dict comprehension

Daniel Fetchinson

2/1/2008 6:19:00 AM

> > Hi folks,
> >
> > There is a withdrawn PEP about a new syntax for dict comprehension:
> > http://www.python.org/dev/peps... which says:
> >
> > "Substantially all of its benefits were subsumed by generator
> > expressions coupled with the dict() constructor."
> >
> > What does the author mean here? What's the Preferably One Way (TM) to
> > do something analogous to a dict comprehension?
> >
> See about generator expressions in
> http://www.python.org/doc/2.4/whatsnew/....
>
> The dict builtin can build a dictionary from a list (or iterator or
> generator creating a list) of tuples. Put them together and get what
> you might be tempted to call a dictionary comprehension. For instance:
>
> >>> dict((i,i*i) for i in range(10))
> {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}

Neat!