朱莉娅:如何在朱莉娅中随机排列一个向量? [英] JULIA : How to permute randomly a vector in julia?

问题描述

我有一个随机数向量，我想使用randperm()函数随机置换如下，但它不起作用.

l have a vector of random numbers that l want to permute randomly using randperm() function as follows but it's not working.

X=rand(100000) # a vector of 100000 random elements
Y=randperm(X) # want to permute randomly the vector x

返回的错误是: 错误:MethodError:没有与randperm(:: Array {Float64,1})匹配的方法 在./boot.jl:237的eval(:: Module，:: Any)中

the returned error is : ERROR: MethodError: no method matching randperm(::Array{Float64,1}) in eval(::Module, ::Any) at ./boot.jl:237

谢谢

推荐答案

基于文档 randperm()接受整数n并给出长度为n的排列.您可以使用以下顺序对原始向量进行重新排序:

Based on the docs the randperm() accepts an integer n and gives a permutation of length n. You can use this ordering to then reorder your original vector:

julia> X = collect(1:5)
5-element Array{Int64,1}:
 1
 2
 3
 4
 5

julia> Y = X[randperm(length(X))]
5-element Array{Int64,1}:
 3
 4
 1
 2
 5

您始终可以通过在REPL中键入?function_name来检查文档.

You can always check the docs by typing ?function_name in the REPL.

如果您的唯一目标是随机置换向量，则也可以使用shuffle():

If your only goal is to randomly permute the vector, you can also use shuffle():

julia> shuffle(X)
5-element Array{Int64,1}:
 5
 4
 1
 2
 3

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