r - 数据框中的条件出现计算

Question

考虑下面的数据框(2 列:id 和 val)，我试图找到一种快速方法来计算唯一事件中 val 列中元素“boo”的出现情况。事件在 id 列中表示。独特的事件是:a、b、c、d

id<-c("a","a","a","a","b","b","c","c","c","d")
val<-c("boo","sd","ssd","df","boo","ksdj","boo","sdjhf","df","boo")
x<-data.frame(id,val)

因此这里的结果应该是 4，因为“boo”出现在所有事件中:a,b,c,d。

Count("boo") =4

示例2

id<-c("a","a","a","a","b","b","c","c","c","d")
val<-c("boo","sd","ssd","df","boo","ksdj","boo","sdjhf","boo","sgfsc")
x<-data.frame(id,val)

Count("boo") =3

我只需要使用 R 库中的包来执行此操作。

谢谢。

Answer 1

对于使用基本 R 的 boo 的唯一计数，可以这样做

sum(with(x, tapply(val, id, function(x) any(x == "boo"))))
## [1] 4