我想调用一个函数,但是根据情况,我可能会使用其他参数来调用它,也可能不使用.这是一个简单的示例:
I want to call a function but depending on the situation I might call it with extra arguments or not. Here is a simple example:
FUN <- function(arg1 = "default1", arg2 = "default2", arg3 = "default3") print(list(arg1, arg2, arg3)) x1 <- "hi" x2 <- TRUE x3 <- 1:3 use.arg3 <- FALSE # This will decide if `x3` is used or not. if (use.arg3) { FUN(arg1 = x1, arg2 = x2, arg3 = x3) } else { FUN(arg1 = x1, arg2 = x2) }虽然代码很清楚,但感觉有点多余.还要想像一下,如果我有类似的 use.arg1 和 use.arg2 变量,那么我将遇到各种各样的可能性(8)...
While the code is clear, it feels a little redundant. Also imagine that if I had similar use.arg1 and use.arg2 variables, I would have an ugly mix of possibilities (8)...
我在下面发布了一个解决方案,但是我发现它有点复杂,以至于我总是很难记住确切的语法.
I have a solution posted below but I find it a little complicated, to the point that I always struggle to remember the exact syntax.
如果您有更好的主意,谢谢您的分享.
If you have a better idea, thank you for sharing.
推荐答案一种解决方案是在构建具有适当参数的列表后使用 do.call :
One solution is to use do.call after building a list with the proper arguments:
do.call(FUN, c(list(arg1 = x1, arg2 = x2), # unconditional args list(arg3 = x3)[use.arg3])) # conditional arg它可以很好地推广到多种情况:
And it generalizes well to multiple conditions:
do.call(FUN, c(list(arg1 = x1)[use.arg1] # conditional arg list(arg2 = x2)[use.arg2] # conditional arg list(arg3 = x3)[use.arg3])) # conditional arg更多推荐
在函数调用中有条件地包含参数
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