[r] Sort columns of a dataframe by column name

This is possibly a simple question, but I do not know how to order columns alphabetically.

test = data.frame(C = c(0, 2, 4, 7, 8), A = c(4, 2, 4, 7, 8), B = c(1, 3, 8, 3, 2))

#   C A B
# 1 0 4 1
# 2 2 2 3
# 3 4 4 8
# 4 7 7 3
# 5 8 8 2

I like to order the columns by column names alphabetically, to achieve

#   A B C
# 1 4 1 0
# 2 2 3 2
# 3 4 8 4
# 4 7 3 7
# 5 8 2 8

For others I want my own defined order:

#   B A C
# 1 4 1 0
# 2 2 3 2
# 3 4 8 4
# 4 7 3 7
# 5 8 2 8

Please note that my datasets are huge, with 10000 variables. So the process needs to be more automated.

So to have a specific column come first, then the rest alphabetically, I'd propose this solution:

test[, c("myFirstColumn", sort(setdiff(names(test), "myFirstColumn")))]

An alternative option is to use str_sort() from library stringr, with the argument numeric = TRUE. This will correctly order column that include numbers not just alphabetically:

str_sort(c("V3", "V1", "V10"), numeric = TRUE)

# [1] V1 V3 V11

  test[,sort(names(test))]

sort on names of columns can work easily.

Here is what I found out to achieve a similar problem with my data set.

First, do what James mentioned above, i.e.

test[ , order(names(test))]

Second, use the everything() function in dplyr to move specific columns of interest (e.g., "D", "G", "K") at the beginning of the data frame, putting the alphabetically ordered columns after those ones.

select(test, D, G, K, everything())

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If you only want one or more columns in the front and don't care about the order of the rest:

require(dplyr)
test %>%
  select(B, everything())

Similar to other syntax above but for learning - can you sort by column names?

sort(colnames(test[1:ncol(test)] ))

test = data.frame(C=c(0,2,4, 7, 8), A=c(4,2,4, 7, 8), B=c(1, 3, 8,3,2))

Using the simple following function replacement can be performed (but only if data frame does not have many columns):

test <- test[, c("A", "B", "C")]

for others:

test <- test[, c("B", "A", "C")]

Here's the obligatory dplyr answer in case somebody wants to do this with the pipe.

test %>% 
    select(sort(names(.)))