r - 根据上一行有条件地重命名该值

Question

我有一个数据框df:

Event       Code
Picture     no$
Picture     value
Picture     $
Picture     value
Picture     no$
Picture     value
Picture     no$
Picture     value
Picture     $
Picture     value

我想根据上一行将value重命名为reward或no_reward。如果是$则奖励，如果no$则no_reward

最好的方法是什么？

Answer 1

另一个想法，

df1$Code[c(FALSE, TRUE)] <- ifelse(df1$Code[c(TRUE, FALSE)] == 'no$', 'no_reward', 'reward')
df1
#     Event      Code
#1  Picture       no$
#2  Picture no_reward
#3  Picture         $
#4  Picture    reward
#5  Picture       no$
#6  Picture no_reward
#7  Picture       no$
#8  Picture no_reward
#9  Picture         $
#10 Picture    reward

注意:这假设对于每个 $ 或 no$，后面都会有一个 值