通过非唯一ID选择数据帧的子集

Question

假设我有一个像这样的数据帧:

df <- data.frame (id = c("a", "b", "a", "c", "e", "d", "e"), n=1:7)

和像这样的id的向量:

v <- c("a", "b")

如何选择与v中的id匹配的数据帧行？我不能将id列用于rownames,因为它们不是唯一的.当我尝试时,我得到:

 rownames(df) <- df[["id"]]
Error in `row.names<-.data.frame`(`*tmp*`, value = c(1L, 2L, 1L, 3L, 5L,  : 
  duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique values when setting 'row.names': ‘a’, ‘e’ 

Answer 1

使用

df[df$id %in% v,]

Answer 2

这应该做你想要的:

ndx = which(df$id %in% v)
df[ndx,]