R根据另一列中的条件选择行

Question

如何选择ID至少包含一个B的所有行？

df<-cbind(c(1,1,1,1,1,2,2,2,2,3,3),c("A","A","B","A","A","B","A","A","B","A","A"))
colnames(df)<-cbind("ID","ITEM")
df

Answer 1

不确定这是否是您的意思，但是：

df[df[, 2]=="B", ]

Answer 2

如果您构建数据框架而不是使用列表，这很容易。

library(dplyr)
df<-data.frame(ID = c(1,1,1,1,1,2,2,2,2,3,3),ITEM=c("A","A","B","A","A","B","A","A","B","A","A"));

df %>% filter(ITEM == "B");