假设我们在R中有这个数据框:
df <- data.frame(id = c(rep(1,5), rep(2, 3), rep(3, 4), rep(4, 2)), brand = c("A", "B", "A", "D", "Closed", "B", "C", "D", "D", "A", "B", "Closed", "C", "Closed"))
> df
# id brand
#1 1 A
#2 1 B
#3 1 A
#4 1 D
#5 1 Closed
#6 2 B
#7 2 C
#8 2 D
#9 3 D
#10 3 A
#11 3 B
#12 3 Closed
#13 4 C
#14 4 Closed
我想创建一个新变量来表示从当前行到下一行的品牌列中的更改,但这必须仅在每个ID号内发生.
我创建了新列:
df$brand_chg <- "" …