重塑视图的功能? [英] Function for Reshape View?

问题描述

在 Julia v0.5 中，如何创建一个类似于 reshape 但返回视图的函数?ArrayViews.jl 有一个 reshape_view 函数，但它似乎与新的 view 函数不直接兼容.我只想 reshape u 到一些我不知道尺寸的元组 sizeu .

In Julia v0.5, how do you make a function which is like reshape but instead returns a view? ArrayViews.jl has a reshape_view function but it doesn't seem directly compatible with the new view function. I just want to reshape u to some tuple sizeu where I don't know the dimensions.

推荐答案

如果你重塑一个视图"，输出就是一个重塑后的视图".

If you reshape a 'view', the output is a reshaped 'view'.

如果您的初始变量是一个普通数组，您可以在函数调用期间将其转换为动态"视图.

If your initial variable is a normal array, you can convert it to a view 'on the fly' during your function call.

根据您后来的评论，此操作期间没有重新分配:您可以使用 pointer 函数确认这一点.对象并不相同，因为它们被解释为指向不同类型"的指针，但内存地址是相同的.

There are no reallocations during this operation, as per your later comment: you can confirm this with the pointer function. The objects aren't the same, in the sense that they are interpreted as pointers to a different 'type', but the memory address is the same.

julia> A = ones(5,5,5); B = view(A, 2:4, 2:4, 2:4); C = reshape(B, 1, 27);

julia> is(B,C)
false

julia> pointer(B)
Ptr{Float64} @0x00007ff51e8b1ac8

julia> pointer(C)
Ptr{Float64} @0x00007ff51e8b1ac8

julia> C[1:5] = zeros(1,5);

julia> A[:,:,2]
5×5 Array{Float64,2}:
 1.0  1.0  1.0  1.0  1.0
 1.0  0.0  0.0  1.0  1.0
 1.0  0.0  0.0  1.0  1.0
 1.0  0.0  1.0  1.0  1.0
 1.0  1.0  1.0  1.0  1.0

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