R函数内修改变量 [英] modify variable within R function

问题描述

如何修改一个参数传递给R中的函数吗？在C ++中，这将通过引用传递。

How do I modify an argument being passed to a function in R? In C++ this would be pass by reference.

g=4
abc <- function(x) {x<-5}
abc(g)

我想先按g 设置为5。

推荐答案

有办法为@Dason表现，但真的！ - 你不应该

There are ways as @Dason showed, but really - you shouldn't!

R的整个模式是按值传递。 @Rory刚刚发布了正常的方式来处理它 - 刚刚返回修改后的值...

The whole paradigm of R is to "pass by value". @Rory just posted the normal way to handle it - just return the modified value...

环境典型地是可以通过在R参考传递的唯一对象。

Environments are typically the only objects that can be passed by reference in R.

但是最近称为引用类新的对象已被添加至R（它们使用的环境中）。他们可以修改它们的值（但以受控方式）。你可能要考虑使用它们，如果你真的觉得有必要...

But lately new objects called reference classes have been added to R (they use environments). They can modify their values (but in a controlled way). You might want to look into using them if you really feel the need...

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