如何在 R 中从第二行开始将值从一列复制到另一列

Question

I'm trying to copy values from one column to a new column in R, starting from the second column onwards.

I've tried df$B <- df$A[-1,] but since it eliminates one of the values, the column will not have the same length anymore.

Ie, what I need is the following (create column B based on column A).

   A  B
1  a  b
2  b  c
3  c  d
4  d  e
5  e  f
6  f  g
7  g  h
8  h  i
9  i  j
10 j  NA

Answer 1

You can use any of the option below:

df$B <- dplyr::lead(df$A)
df$B <- data.table::shift(df$A, type = "lead")
df$B <- c(tail(df$A, -1), NA)
df$B <- c(df$A[-1], NA)

Answer 2

We can also do

df <- transform(df, B = c(A[-1], NA))