dplyr的mutate_each在函数中工作,但matches()没有找到参数 [英] dplyr's mutate_each within function works but matches() does not find argument
问题描述
当尝试解决这个问题我遇到了 mutate_each
的 dplyr
的问题。我想在函数中使用它并传递参数。对于 funs()
而不是 matches()
。
When trying to solve this problem I encountered a problem with mutate_each
of dplyr
. I wanted to use it within a function and pass arguments to it. It was successful for funs()
but not for matches()
.
让我展示一个简单的例子,其中任务是附加一些变量的值。
Let me show a simple example where the task is to append some tag the values of some variables.
library(dplyr)
mydf <- data.frame(this_var1 = c("a", "b", "c", "d", "e"),
this_var2 = c("b", "c", "d", "e", "f"),
that_var1 = c("x", "y", "z", "w", "u"))
mymutate1 <- function(data, tag) {
data %>% mutate_each(funs(paste0(., tag)))
}
mymutate1(mydf, "_foo")
this_var1 this_var2 that_var1
1 a_foo b_foo x_foo
2 b_foo c_foo y_foo
3 c_foo d_foo z_foo
4 d_foo e_foo w_foo
5 e_foo f_foo u_foo
这样做就像一个魅力。但是,如果我尝试控制变量应该应用哪个变量,它将失败。
This works like a charm. However, if I try to control also for which variables the transformation should be applied it fails.
mymutate2 <- function(data, tag, m) {
data %>% mutate_each(funs(paste0(., tag)), matches(m))
}
mymutate2(mydf, "_foo", "this")
这会产生以下错误: is.string(match)中的错误:对象'm'未找到
。为什么找到标签
而 m
不是?
This gives the following error: Error in is.string(match) : object 'm' not found
. Why is tag
found whereas m
not?
代码本身正常工作:
mydf %>% mutate_each(funs(paste0(., "_foo")), matches("this"))
this_var1 this_var2 that_var1
1 a_foo b_foo x
2 b_foo c_foo y
3 c_foo d_foo z
4 d_foo e_foo w
5 e_foo f_foo u
推荐答案
您将要使用标准评估(SE)版本的 mutate_each
- 也就是说, mutate_each _
:
You are going to want to use the Standard Evaluation (SE) version of mutate_each
-- that is, mutate_each_
:
mymutate2 <- function(data, tag, m) {
data %>% mutate_each_(funs(paste0(., tag)), ~matches(m))
}
为了更加清楚,以下是等价的:
For additional clarity, the following is equivalent:
mymutate3 <- function(data, tag, m) {
data %>% mutate_each_(~paste0(., tag), ~matches(m))
}
根据小插曲:
最好使用公式[〜
而不是 quote )
或使用字符串],因为一个公式捕获要评估的表达式以及它应该被评估的环境。使用公式以外的其他任何内容都会失败,因为它不知道要查找哪个环境。
"It’s best to use a formula [ ~
as opposed to quote()
or using strings ""
], because a formula captures both the expression to evaluate, and the environment in which it should be a evaluated...Using anything other than a formula will fail because it doesn't know which environment to look in."
这篇关于dplyr的mutate_each在函数中工作,但matches()没有找到参数的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!