Add (insert) a column between two columns in a data.frame

I would suggest you to use the function add_column() from the tibble package.

library(tibble)
dataset <- data.frame(a = 1:5, b = 2:6, c=3:7)
add_column(dataset, d = 4:8, .after = 2)

Note that you can use column names instead of column index :

add_column(dataset, d = 4:8, .after = "b")

Or use argument .before instead of .after if more convenient.

add_column(dataset, d = 4:8, .before = "c")

Add in your new column:

df$d <- list/data

Then you can reorder them.

df <- df[, c("a", "b", "d", "c")]

You can reorder the columns with [, or present the columns in the order that you want.

d <- data.frame(a=1:4, b=5:8, c=9:12)
target <- which(names(d) == 'b')[1]
cbind(d[,1:target,drop=F], data.frame(d=12:15), d[,(target+1):length(d),drop=F])

  a b  d  c
1 1 5 12  9
2 2 6 13 10
3 3 7 14 11
4 4 8 15 12

Presuming that c always immediately follows b, this code will add a column after b no matter where b is in your data.frame.

> test <- data.frame(a=1,b=1,c=1)
> test
  a b c
1 1 1 1

> bspot <- which(names(test)=="b")

> data.frame(test[1:bspot],d=2,test[(bspot+1):ncol(test)])
  a b d c
1 1 1 2 1

Or possibly more naturally:

data.frame(append(test, list(d=2), after=match("b", names(test))))