我使用下面的代码生成一个简单的汇总表:
# Data
data("mtcars")
# Lib
require(dplyr)
# Summary
mt_sum <- mtcars %>%
group_by(am) %>%
summarise_each(funs(min, mean, median, max), mpg, cyl) %>%
mutate(am = as.character(am)) %>%
left_join(y = as.data.frame(table(mtcars$am),
stringsAsFactors = FALSE),
by = c("am" = "Var1"))
该代码产生所需的结果:
> head(mt_sum)
Source: local data frame [2 x 10]
am mpg_min cyl_min mpg_mean cyl_mean mpg_median cyl_median mpg_max cyl_max Freq
(chr) (dbl) (dbl) (dbl) (dbl) (dbl) (dbl) (dbl) (dbl) (int)
1 0 10.4 4 17.14737 6.947368 17.3 8 24.4 8 19
2 1 15.0 4 24.39231 5.076923 22.8 4 33.9 8 13
但是,我对列的排序方式不满意。我特别想:
按名称对列进行排序
通过以下方式实现这一点select()
in dplyr
所需订单
所需的顺序如下所示:
> names(mt_sum)[order(names(mt_sum))]
[1] "am" "cyl_max" "cyl_mean" "cyl_median" "cyl_min" "Freq" "mpg_max"
[8] "mpg_mean" "mpg_median" "mpg_min"
Attempts
理想情况下,我想通过names(mt_sum)[order(names(mt_sum))]
对列进行排序的方法select()
。但是代码:
mt_sum <- mtcars %>%
group_by(am) %>%
summarise_each(funs(min, mean, median, max), mpg, cyl) %>%
mutate(am = as.character(am)) %>%
left_join(y = as.data.frame(table(mtcars$am),
stringsAsFactors = FALSE),
by = c("am" = "Var1")) %>%
select(names(.)[order(names(.))])
将返回预期的错误:
Error: All select() inputs must resolve to integer column positions.
The following do not:
* names(.)[order(names(.))]
在我的真实数据中,我生成了大量的摘要列。因此我的问题是,如何动态地将排序的列名称传递给select()
in dplyr
所以它会理解并应用到data.frame
在眼前?
我的重点是找出一种将动态生成的列名称传递给select()
。我知道我可以对其中的列进行排序base
或通过键入名称,如所讨论的here https://stackoverflow.com/questions/5620885/how-does-one-reorder-columns-in-r.