朱莉娅有外部地图功能吗? [英] Is there outer map function in Julia?

问题描述

我正在尝试构造四个向量的所有可能组合(模型中的参数)，这将给我一个大的nx4矩阵，然后可以对每个参数(行)进行仿真.在R中，我可以通过使用Mathematica风格的expand.grid来实现此目的，我可以在vcat中使用外部乘积，并使用hcat减少输出.

I am trying to construct all possible combinations of four vectors (parameters in a model) that would give me a big nx4 matrix and I could then run simulation on each set (row) of parameters. In R I would achieve this by using expand.grid in Mathematica style, I could use something like outer product with vcat and reduce the output using hcat.

R或外部映射函数中是否有expand.grid的函数类似物?

Is there some function analog of expand.grid from R or outer map function?

玩具示例:

A = [1 2]
B = [3 4]

some magic

output = [1 3, 1 4, 2 3, 2 4]

推荐答案

使用Iterators程序包，看起来可能像这样:

Using the Iterators package, it might look like this:

using Iterators
for p in product([1,2], [3,4])
    println(p)
end

，其中您将用算法替换println.如果要获得所有组合的集合很重要，也可以使用collect.

where you would replace println with your algorithm. You can also use collect if it's important to get the set of all combinations.

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