On Thu, 12 Apr 2012 12:35:21 -0600 Ian Kelly <ian.g.ke...@gmail.com> wrote:
> On Thu, Apr 12, 2012 at 11:59 AM, John Nagle <na...@animats.com> wrote: > > On 4/12/2012 10:41 AM, Roy Smith wrote: > >> > >> Is there a simple way to deep merge two dicts? I'm looking for Perl's > >> Hash::Merge (http://search.cpan.org/~dmuey/Hash-Merge-0.12/Merge.pm) > >> in Python. > > > > > > def dmerge(a, b) : > > for k in a : > > v = a[k] > > if isinstance(v, dict) and k in b: > > dmerge(v, b[k]) > > a.update(b) > > That doesn't work. After b[k] is recursively merged into a[k], the > call "a.update(b)" copies b[k] into a[k], discarding the merged dict. > Try this: > > def dmerge(a, b): > for k, v in b.items(): > if isinstance(v, dict) and k in a: > dmerge(a[k], v) > else: > a[k] = v > I think you also have to check if a[k] is a dict before making the recursive call, else for example dmerge({'a': 1}, {'a': {'b': 1}}) fails with a TypeError. In that case the third line above should read: if k in a and isinstance(a[k], dict) and isinstance(v, dict): Regards, John -- http://mail.python.org/mailman/listinfo/python-list
