[Tutor] Python creating trie
steve at pearwood.info
Sun Nov 12 06:48:33 EST 2017
On Sun, Nov 12, 2017 at 02:37:06AM -0800, anish singh wrote:
> Can someone explain me this code to create a trie
> from words?
Not really. What makes this a trie? Where did you get this code from?
> import collections
> words = ["bad", "sad", "abyss"]
> Trie = lambda: collections.defaultdict(Trie)
> trie = Trie()
> END = True
> for i, word in enumerate(words):
> reduce(dict.__getitem__, word, trie)[END] = i
> I am not able to understand lambda usage and reduce
> function here.
The lambda is exactly equivalent to:
# Trie = lambda: collections.defaultdict(Trie)
Does that help?
The call to reduce (inside the loop) can be re-written as (untested):
# for i, word in enumerate(words):
# reduce(dict.__getitem__, word, trie)[END] = i
for i, word in enumerate(words):
value = trie
for item in word:
value = value[item]
value[END] = i
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