julia - 如何在 Julia 中将二维数组转换为一维数组

Question

我有这个二维数组:a = [ (1,2) (2,3) ; (3,4) (4,5)] 我想转换成:

(1, 2)
(2, 3)
(3, 4)
(4, 5)
#1D Array

我如何在 Julia 中执行此操作？

Answer 1

我还会评论其​​他方法。

前两个遍历 Matrix 列而不是行:

julia> a[:]
4-element Array{Tuple{Int64,Int64},1}:
 (1, 2)
 (3, 4)
 (2, 3)
 (4, 5)

复制数据和:

julia> vec(a)
4-element Array{Tuple{Int64,Int64},1}:
 (1, 2)
 (3, 4)
 (2, 3)
 (4, 5)

它与 a 共享底层数据。这是一个结果:

julia> b = vec(a)
4-element Array{Tuple{Int64,Int64},1}:
 (1, 2)
 (3, 4)
 (2, 3)
 (4, 5)

julia> b[1] = (100, 100)
(100, 100)

julia> b
4-element Array{Tuple{Int64,Int64},1}:
 (100, 100)
 (3, 4)
 (2, 3)
 (4, 5)

julia> a
2×2 Array{Tuple{Int64,Int64},2}:
 (100, 100)  (2, 3)
 (3, 4)      (4, 5)

您可以使用显式理解，这允许您以两种方式进行操作:

julia> [a[i,j] for j in axes(a, 2) for i in axes(a, 1)]
4-element Array{Tuple{Int64,Int64},1}:
 (1, 2)
 (3, 4)
 (2, 3)
 (4, 5)

julia> [a[i,j] for i in axes(a, 1) for j in axes(a, 2)]
4-element Array{Tuple{Int64,Int64},1}:
 (1, 2)
 (2, 3)
 (3, 4)
 (4, 5)

最后你可以使用 vcat，同样是两种方式:

julia> reduce(vcat, eachrow(a))
4-element Array{Tuple{Int64,Int64},1}:
 (1, 2)
 (2, 3)
 (3, 4)
 (4, 5)

julia> reduce(vcat, eachcol(a))
4-element Array{Tuple{Int64,Int64},1}:
 (1, 2)
 (3, 4)
 (2, 3)
 (4, 5)