Order column names in ascending order within dplyr chain - r

Question

I have this data.frame:
df <- structure(list(att_number = structure(1:3, .Label = c("0", "1",
"2"), class = "factor"), `1` = structure(c(2L, 3L, 1L), .Label = c("1026891",
"412419", "424869"), class = "factor"), `10` = structure(c(2L,
1L, 3L), .Label = c("235067", "546686", "92324"), class = "factor"),
`2` = structure(c(3L, 1L, 2L), .Label = c("12729", "7569",
"9149"), class = "factor")), .Names = c("att_number", "1",
"10", "2"), row.names = c(NA, -3L), class = "data.frame")
It looks like this having numbers as the column names.
att_number 1 10 2
0 412419 546686 9149
1 424869 235067 12729
2 1026891 92324 7569
Within a dplyr chain, I would like to order the columns in ascending order, like this:
att_number 1 2 10
0 412419 9149 546686
1 424869 12729 235067
2 1026891 7569 7569
I've tried using select_, but it doesn't want to work according to plan. Any idea on how I can do this? Here's my feeble attempt:
names_order <- names(df)[-1] %>%
as.numeric %>%
.[order(.)] %>%
as.character %>%
c('att_number', .)
df %>%
select_(.dots = names_order)
Error: Position must be between 0 and n

Answer 1

Update:
For newer versions of dplyr (>= 0.7.0):
library(tidyverse)
sort_names <- function(data) {
name <- names(data)
chars <- keep(name, grepl, pattern = "[^0-9]") %>% sort()
nums <- discard(name, grepl, pattern = "[^0-9]") %>%
as.numeric() %>%
sort() %>%
sprintf("%s", .)
select(data, !!!c(chars, nums))
}
sort_names(df)
Original:
You need back ticks around the numeric column names to stop select from trying to interpret them as column positions:
library(tidyverse)
sort_names <- function(data) {
name <- names(data)
chars <- keep(name, grepl, pattern = "[^0-9]") %>% sort()
nums <- discard(name, grepl, pattern = "[^0-9]") %>%
as.numeric() %>%
sort() %>%
sprintf("`%s`", .)
select_(data, .dots = c(chars, nums))
}
sort_names(df)