dictionary - Julia double for 循环，遍历字典

Question

我刚刚开始使用 Julia。据我了解，Julia 允许您在一行上声明多个 for 循环。

例如:

for i = 1:2, j = [-1,-2]
    println((i, j))
end

会导致这样的结果:

(1,-1)
(1,-2)
(2,-1)
(2,-2)

我现在正在做类似的事情，但是在循环字典时。我声明如下:

rename = function(x)
    x["num"] = -x["num"]
    x
end

players1 = [["num" => 1],["num" => 2]]
players2 = map(rename, copy(players1)) # = [["num" => -1],["num" => -2]]

奇怪的是，对我来说，当我这样做时:

for i=players1, j=players2
    println(i, j)
end

为什么我没有得到这个输出？

["num"=>1]["num"=>-1]
["num"=>1]["num"=>-2]
["num"=>2]["num"=>-1]
["num"=>2]["num"=>-2] 

Answer 1

啊。在这种情况下，map 函数仍然需要deepcopy。

这段代码似乎确实有效。

rename = function(x)
    x["num"] = -x["num"]
    x
end

players1 = [["num" => 1],["num" => 2]]
players2 = map(rename, deepcopy(players1))

for i=players1, j=players2
    println(i, j)
end