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

问题描述

在Julia v0.5中，您如何制作类似于重塑形状但返回视图的函数? ArrayViews.jl具有reshape_view函数，但似乎与新的view函数不直接兼容.我只想reshape u到一些元组sizeu，而我不知道其尺寸.

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

如果重塑视图"，则输出是重塑的视图".

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

如果初始变量是普通数组，则可以在函数调用期间将其转换为即时"视图.

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

在此操作期间没有重新分配，如您稍后的评论所述:您可以使用pointer功能确认这一点.从某种意义上说，它们被解释为指向不同类型"的指针，但对象是不同的，但是内存地址是相同的.

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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