r - How to add new column to an dataframe (to the front not end)?

Question

How to add a new variable to an existing data frame, but I want to add to the front not end. eg. my dataframe is

b c d
1 2 3
1 2 3
1 2 3

I want to add a new variable a, so the dataframe will looks like

a b c d
0 1 2 3
0 1 2 3
0 1 2 3

Answer 1

Use cbind e.g.

df <- data.frame(b = runif(6), c = rnorm(6))
cbind(a = 0, df)

giving:

> cbind(a = 0, df)
  a         b          c
1 0 0.5437436 -0.1374967
2 0 0.5634469 -1.0777253
3 0 0.9018029 -0.8749269
4 0 0.1649184 -0.4720979
5 0 0.6992595  0.6219001
6 0 0.6907937 -1.7416569