library(purrr)
library(rlang)
#>
#> Attaching package: 'rlang'
#> The following objects are masked from 'package:purrr':
#>
#> %@%, %||%, as_function, flatten, flatten_chr, flatten_dbl,
#> flatten_int, flatten_lgl, invoke, list_along, modify, prepend,
#> rep_along, splice
library(dplyr)
#>
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>
#> filter, lag
#> The following objects are masked from 'package:base':
#>
#> intersect, setdiff, setequal, union
back <- function(data, ...){
dots <- quos(...)
# negate each expression
ndots <- map(dots, function(q) expr(-!!q) )
# select the negated (rm the columns) and then select them back
select( data, !!!ndots, !!!dots )
}
front <- function(data, ...){
select( data, ..., everything() )
}
back(iris, Species) %>% head
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> 1 5.1 3.5 1.4 0.2 setosa
#> 2 4.9 3.0 1.4 0.2 setosa
#> 3 4.7 3.2 1.3 0.2 setosa
#> 4 4.6 3.1 1.5 0.2 setosa
#> 5 5.0 3.6 1.4 0.2 setosa
#> 6 5.4 3.9 1.7 0.4 setosa
back(iris, Species, starts_with("Petal")) %>% head
#> Sepal.Length Sepal.Width Species Petal.Length Petal.Width
#> 1 5.1 3.5 setosa 1.4 0.2
#> 2 4.9 3.0 setosa 1.4 0.2
#> 3 4.7 3.2 setosa 1.3 0.2
#> 4 4.6 3.1 setosa 1.5 0.2
#> 5 5.0 3.6 setosa 1.4 0.2
#> 6 5.4 3.9 setosa 1.7 0.4
front(iris, Species) %>% head
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> 1 setosa 5.1 3.5 1.4 0.2
#> 2 setosa 4.9 3.0 1.4 0.2
#> 3 setosa 4.7 3.2 1.3 0.2
#> 4 setosa 4.6 3.1 1.5 0.2
#> 5 setosa 5.0 3.6 1.4 0.2
#> 6 setosa 5.4 3.9 1.7 0.4Created on 2018-04-23 by the reprex package (v0.2.0).