r - 检查第 1 列值之前是否出现在具有不同第 2 列值的数据集中

Question

我有这样的数据集

df <- data.frame(ID = c("m1","m2","m3","m4","m5","m6","m2","m3","m5","m6","m1","m4","m5"),
                 Year = c(1,1,1,1,1,1,2,2,2,2,3,3,3))

并想检查该 ID 是否出现在前一年。现在我有一个似乎可以工作的代码

df$Check <- apply(df, 1, function(x) x["ID"] %in% df[df$Year == (as.numeric(x["Year"]) - 1), "ID"])

但考虑到我的数据集有 300 万行，此函数运行时间太长。有更好的选择吗？？

Answer 1

尝试

library(dplyr)
dfs <- split(df$ID, df$Year);
df$check <- unlist(mapply(`%in%`, dfs,  lag(dfs)))