Sorting a list of dictionaries by dictionary key

[Alex Martelli]

Tim Chase <python.list at tim.thechases.com> wrote:

> > assuming that DateTime returns something that compares correctly, you can
> > do something like:
> > 
> >     def sortkey(item):
> >         return item.get("from_datetime")
> > 
> >     data.sort(key=sortkey)
> > 
> > (assuming Python 2.4 or later)
> 
> Building on Fredrik's solution, for 2.3 (or earlier?), you 
> can use
> 
> data.sort(lambda a,b: cmp(a['from_datetime'], 
> b['from_datetime']))

...and get a potentially very slow sort, if the list is long.  Much
faster:

_aux = [ (d['from_datetime'], i, d) for (i, d) in enumerate(data) ]
_aux.sort()
data[:] = [ t[-1] for t in _aux ]


Google Search for DSU or [Decorate Sort Undecorate] ...


Alex