The idea of Ngram is that it is a view of N string of length k without
using k times as much memory. I would like to preform operation the set of
Ngram string, let's say unique(). In those cases I expect it to be treat as
1 dimension Array of String.
I am making some progress with similar defined like this
Base.similar(s::Ngram) = Array(ASCIIString)
Base.similar(a::Ngram, dims::Dims) = Array(ASCIIString, dims)
Base.similar{T}(a::Ngram, ::Type{T}, dims::Dims) = Array(T, dims)
So far I have successfully applied, map(), maximum(), unique(), etc. sort()
gives an error though
In [428]:
sort(s)
access to undefined reference
while loading In[428], in expression starting on line 1
in sort at sort.jl:342
Wai yip
On Thursday, February 5, 2015 at 3:47:26 AM UTC-8, Milan Bouchet-Valat
wrote:
>
> Le mercredi 04 février 2015 à 23:11 -0800, Wai Yip Tung a écrit :
>
> I have successfully defined a custom array Ngram.
>
>
>
> type Ngram <: AbstractArray{ASCIIString,1}
>
> seq::ASCIIString
>
> n::Int
>
> end
>
>
>
> function getindex(s::Ngram, i::Int)
>
> s.seq[i:i+s.n-1]
>
> end
>
>
>
> function Base.size(s::Ngram)
>
> length(s.seq) - s.n + 1
>
> end
>
>
>
>
>
> It works as I expected. For example
>
>
>
> In [219]:
>
>
>
>
> ng=SeqUtil.Ngram("hello",2)
>
>
>
> Out[219]:
>
> 4-element Ngram:
> "he"
> "el"
> "ll"
> "lo"
>
>
>
> But it seems in other usage, a corresponding `similar` method is
> necessary
>
>
>
> In [222]:
>
>
>
>
> map(print,ng)
>
>
>
>
> he
>
>
> `similar` has no method matching similar(::Ngram, ::Type{Nothing},
> ::(Int32,))
> while loading In[222], in expression starting on line 1
>
> in similar at abstractarray.jl:116
> in map at abstractarray.jl:1329
>
>
>
> I have read the documentation and I still don't get what I need to do in
> the similar method. You help will be appreciated.
>
> That method should just create an array of the same type, with the same
> element type and dimensions by default, but accepting arguments to override
> these two values. For example, you can see what that function does for
> standard Arrays with: ...@edit <javascript:> similar([1:3]). In the case
> of map(f, ng), the goal is to create an array to hold the result: its
> element type must be that of the result of calling f on an element of ng,
> and its dimensions must be the the same as ng.
>
> The problem with Ngram is that it cannot store the result of calling map()
> on it. So I'm not sure what's the best solution here. Looks like Ngram is
> not really an AbstractArray, only an iterable and indexable, in which
> case a different map() method would be used. Then you wouldn't implement
> similar()., but rather the start()/next()/done() iteration protocol.
>
> Regards
>
