现在已经不推荐使用invoke()，那有什么选择呢?

问题描述

="a" = rlang::invoke() 已被弃用， purrr::invoke() 退役了.如今，以编程方式调用带有参数列表的函数的整洁方法是什么?

rlang::invoke() is now soft-deprecated, purrr::invoke() retired. These days, what is the tidy approach to programmatically calling a function with a list of arguments?

推荐答案

tldr; ；使用exec代替invoke；使用map2加exec代替invoke_map.

tldr; Use exec instead of invoke; use map2 plus exec instead of invoke_map.

已退休的invoke

set.seed(2020)
invoke(rnorm, list(mean = 1, sd = 2), n = 10)
#[1]  1.7539442  1.6030967 -1.1960463 -1.2608118 -4.5930686  2.4411470
#[7]  2.8782420  0.5412445  4.5182627  1.2347336

使用exec

set.seed(2020)
exec(rnorm, n = 10, !!!list(mean = 1, sd = 2))
#[1]  1.7539442  1.6030967 -1.1960463 -1.2608118 -4.5930686  2.4411470
#[7]  2.8782420  0.5412445  4.5182627  1.2347336

---

invoke_map

的示例

同样，您可以将map2与exec结合使用，而不是invoke_map.以前，您将使用invoke_map来使用带有不同参数集的函数

---

Example for invoke_map

Similarly, instead of invoke_map you'd use map2 with exec. Previously, you'd use invoke_map to use a function with different sets of arguments

set.seed(2020)
invoke_map(rnorm, list(list(mean = 0, sd = 1), list(mean = 1, sd = 1)), n = 10)
#    [[1]]
#     [1]  0.3769721  0.3015484 -1.0980232 -1.1304059 -2.7965343  0.7205735
#     [7]  0.9391210 -0.2293777  1.7591313  0.1173668
#
#    [[2]]
#     [1]  0.1468772  1.9092592  2.1963730  0.6284161  0.8767398  2.8000431
#     [7]  2.7039959 -2.0387646 -1.2889749  1.0583035

现在，将map2与exec一起使用

set.seed(2020)
map2(
    list(rnorm),
    list(list(mean = 0, sd = 1), list(mean = 1, sd = 1)),
    function(fn, args) exec(fn, n = 10, !!!args))
#    [[1]]
#     [1]  0.3769721  0.3015484 -1.0980232 -1.1304059 -2.7965343  0.7205735
#     [7]  0.9391210 -0.2293777  1.7591313  0.1173668
#
#    [[2]]
#     [1]  0.1468772  1.9092592  2.1963730  0.6284161  0.8767398  2.8000431
#     [7]  2.7039959 -2.0387646 -1.2889749  1.0583035

可悲的是，map2加exec语法不如invoke_map简洁，但可能更规范.

Sadly, the map2 plus exec syntax is not as concise as invoke_map, but it is perhaps more canonical.

一些注释可以帮助避免在使用map2加exec时出现问题:

A few comments that may help avoid issues when using map2 plus exec:

1. map2的第一个参数必须为list.因此map2(list(rnorm), ...)将起作用.仅提供map2(rnorm, ...)的功能就不会.这与invoke_map不同，invoke_map接受了功能的list和功能本身.
2. 第二个参数必须是参数list s的list. map2将遍历顶级list，然后在exec中使用大爆炸运算符!!!强制拼接函数参数的list.

1. The first argument of map2 must be a list. So map2(list(rnorm), ...) will work. Just providing the function as map2(rnorm, ...) will not. This is different to invoke_map, which accepted both a list of functions and a function itself.
2. The second argument needs to be a list of argument lists. map2 will iterate through the top-level list, and then use the big-bang operator !!! inside exec to force-splice the list of function arguments.

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