One-line Tree In Python
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One-line Tree In Python
1–10 of 38 posts
Re: One-line Tree In Python
#2Jebus that was simple! I wish I'd thought of it.
Re: One-line Tree In Python
#3In Perl, this is called autovivification: https://en.wikipedia.org/wiki/Autovivification
I've wanted something like that in Python at different times... thanks!
edit: Ha! The Wiki article even has basically the same code:
def hash(): return defaultdict(hash)
Re: One-line Tree In Python
#4I would be interest to see this using the __getattr__ rather than __getitem__, so that this is also possible:
users = tree()
users.harold.username = 'hrldcpr'
users.handler.username = 'matthandlersux'Re: One-line Tree In Python
#5This is actually quite elegant and useful. I've done similar things time and time again with code like so:
defaultdict(lambda: defaultdict(int))
Re: One-line Tree In Python
#6I would be interest to see this using the __getattr__ rather than __getitem__, so that this is also possible: users = tree() users.harold.username = 'hrldcpr' users.handler.username = 'matthandlersux'
Well, it's as trivial as you say. Just set __getattr__ = __getitem__ in your tree.
(Note though that there is/was a small bug(?) in CPython: http://bugs.python.org/issue14658)
Re: One-line Tree In Python
#7I would be interest to see this using the __getattr__ rather than __getitem__, so that this is also possible: users = tree() users.harold.username = 'hrldcpr' users.handler.username = 'matthandlersux'
class attrdict(defaultdict):
def __getattr__(self, key): return self[key]
def __setattr__(self, key, val): self[key]=val
def tree(): return attrdict(tree)
Re: One-line Tree In Python
#8In Perl, this is called autovivification: https://en.wikipedia.org/wiki/Autovivification I've wanted something like that in Python at different times... thanks! edit: Ha! The Wiki article even has basically the same code: def hash(): return defaultdict(hash)
wow thanks i was actually really curious if there was a name for this sort of thing! added a note about it to the gist.
i wonder whether it will be made part of more languages as JSON-esque nested objects proliferate in our code and minds.
Re: One-line Tree In Python
#9Neat. Works in Ruby, too.
def tree; Hash.new {|h, k| h[k] = tree }; end
t = tree
t[:foo][:bar] = "foobar" # => {:foo=>{:bar=>"foobar"}}
class Tree edit - Thanks!
Re: One-line Tree In Python
#10This is pretty good. I prefer the name I used when I needed it, though.
dicts_all_the_way_down = lambda:defaultdict(dicts_all_the_way_down)