是否有一个Julia等于NumPy的省略号切片语法(...)? [英] Is there a Julia equivalent to NumPy's ellipsis slicing syntax (...)?
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问题描述
在NumPy中,省略号语法用于
填写多个
:
,直到切片说明符的数量与数组的尺寸匹配为止.
filling in a number of
:
until the number of slicing specifiers matches the dimension of the array.
(解释为此答案).
我该如何在Julia中做到这一点?
How can I do that in Julia?
推荐答案
还没有,但是您可以根据需要帮助自己.
Not yet, but you can help yourself if you want.
import Base.getindex, Base.setindex!
const .. = Val{:...}
setindex!{T}(A::AbstractArray{T,1}, x, ::Type{Val{:...}}, n) = A[n] = x
setindex!{T}(A::AbstractArray{T,2}, x, ::Type{Val{:...}}, n) = A[ :, n] = x
setindex!{T}(A::AbstractArray{T,3}, x, ::Type{Val{:...}}, n) = A[ :, :, n] =x
getindex{T}(A::AbstractArray{T,1}, ::Type{Val{:...}}, n) = A[n]
getindex{T}(A::AbstractArray{T,2}, ::Type{Val{:...}}, n) = A[ :, n]
getindex{T}(A::AbstractArray{T,3}, ::Type{Val{:...}}, n) = A[ :, :, n]
那你就可以写
> rand(3,3,3)[.., 1]
3x3 Array{Float64,2}:
0.0750793 0.490528 0.273044
0.470398 0.461376 0.01372
0.311559 0.879684 0.531157
如果要进行更精细的切片,则需要生成/扩展定义或使用分段函数.
If you want more elaborate slicing, you need to generate/expand the definition or use staged functions.
如今,请参见 https://github.com/ChrisRackauckas/EllipsisNotation.jl
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