dictionary - 为什么此haskey()条件始终为false？

我先从字数列表开始：

julia> import Iterators: partition
julia> import StatsBase: countmap
julia> s = split("the lazy fox jumps over the brown dog");
julia> vocab_counter = countmap(s)
Dict{SubString{String},Int64} with 7 entries:
  "brown" => 1
  "lazy"  => 1
  "jumps" => 1
  "the"   => 2
  "fox"   => 1
  "over"  => 1
  "dog"   => 1

然后我要计算否。每个单词ngrams并将其存储在嵌套字典中。外键是ngram，内键是单词，最里面的值是给定单词的ngram计数。

我试过了：

ngram_word_counter = Dict{Tuple,Dict}()
for (word, count) in vocab_counter
    for ng in ngram(word, 2) # bigrams.
        if ! haskey(ngram_word_counter, ng)
            ngram_word_counter[ng] = Dict{String,Int64}()
            ngram_word_counter[ng][word] = 0
        end
        ngram_word_counter[ng][word] += 1
    end
end

这给了我所需的数据结构：

julia> ngram_word_counter
Dict{Tuple,Dict} with 20 entries:
  ('b','r') => Dict("brown"=>1)
  ('t','h') => Dict("the"=>1)
  ('o','w') => Dict("brown"=>1)
  ('z','y') => Dict("lazy"=>1)
  ('o','g') => Dict("dog"=>1)
  ('u','m') => Dict("jumps"=>1)
  ('o','x') => Dict("fox"=>1)
  ('e','r') => Dict("over"=>1)
  ('a','z') => Dict("lazy"=>1)
  ('p','s') => Dict("jumps"=>1)
  ('h','e') => Dict("the"=>1)
  ('d','o') => Dict("dog"=>1)
  ('w','n') => Dict("brown"=>1)
  ('m','p') => Dict("jumps"=>1)
  ('l','a') => Dict("lazy"=>1)
  ('o','v') => Dict("over"=>1)
  ('v','e') => Dict("over"=>1)
  ('r','o') => Dict("brown"=>1)
  ('f','o') => Dict("fox"=>1)
  ('j','u') => Dict("jumps"=>1)

但是请注意，这些值是错误的：

('t','h') => Dict("the"=>1)
('h','e') => Dict("the"=>1)

本来应该：

('t','h') => Dict("the"=>2)
('h','e') => Dict("the"=>2)

自从这个词出现了两次。

仔细查看后，看来haskey(ngram_word_counter, ng)始终为false =（

julia> ngram_word_counter = Dict{Tuple,Dict}()
for (word, count) in vocab_counter
    for ng in ngram(word, 2) # bigrams.
        println(haskey(ngram_word_counter, ng))
    end
end

[出]：

false
false
false
false
false
false
false
false
false
false
false
false
false
false
false
false
false
false
false
false

为什么此haskey()条件始终为假？

最佳答案

TL; DR：应该为ngram_word_counter[ng][word] += count而不是ngram_word_counter[ng][word] += 1。

仅添加1会忽略一个单词出现多次的多重贡献。单词出现的次数被编码为vocab_counter值，这些值进入count循环的变量for中。因此，增量应为count。

以后的调试检查是无效的，并且在通常情况下，调试代码的错误将问题弄混了。预期的检查可能是：

julia> ngram_word_counter = Dict{Tuple,Dict}()
for (word, count) in vocab_counter
    for ng in ngram(word, 2) # bigrams.
        println(haskey(ngram_word_counter, ng))
        ngram_word_counter[ng] = 1
    end
end

关于dictionary - 为什么此haskey()条件始终为false？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/43115581/