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

Answer 1

The previous answers show 3 approaches

1. By creating a new data frame
2. By using "cbind"
3. By adding column "a", and sort data frame by columns using column names or indexes

Let me show #4 approach "By using "cbind" and "rename" that works for my case

1. Create data frame

df <- data.frame(b = c(1, 1, 1), c = c(2, 2, 2), d = c(3, 3, 3))

2. Get values for "new" column

new_column = c(0, 0, 0)

3. Combine "new" column with existed

df <- cbind(new_column, df)

4. Rename "new" column name

colnames(df)[1] <- "a"