是否有与 NumPy 的省略号切片语法 (...) 等效的 Julia? [英] Is there a Julia equivalent to NumPy's ellipsis slicing syntax (...)?

问题描述

在 NumPy 中，省略号语法 用于

In NumPy, the ellipsis syntax is for

填写多个:，直到切片说明符的个数与数组的维度相匹配.

filling in a number of : until the number of slicing specifiers matches the dimension of the array.

(转述这个答案).

我如何在 Julia 中做到这一点?

How can I do that in Julia?

推荐答案

还没有，但如果你愿意，你可以自己动手.

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]

那你就可以写了

    > 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

如果您想要更精细的切片，您需要生成/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，请参阅 https://github.com/ChrisRackauckas/EllipsisNotation.jl

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