r - dplyr 中单个数据的概率

Question

示例：具有许多个人和 3 个变量的数据框：年份（整数）、性别（因子：男/女）和工会（因子：是/否）。我想计算在给定年份和性别的情况下成为工会成员的概率。我通常用聚合（）来做到这一点。我是否一直在这样做，我正在寻找一种在 dplyr 中快速快速的方法。

亲切的问候，彼得

Answer 1

这dplyr相当于@droopy的答案：

tbl_df( x ) %.%
  group_by( year, gender ) %.%
  summarise( P = mean(union == "yes") )

Source: local data frame [8 x 3]
Groups: year

  year gender   P
1 2001 female 1.0
2 2001   male 0.5
3 2002 female 0.5
4 2002   male 0.0
5 2003 female 0.0
6 2003   male 0.5
7 2004 female 0.5
8 2004   male 0.0

...为了完整起见，还有data.table解决方案：

as.data.table(x)[ , list( P = mean( union == "yes" ) ), by = list( year, gender )  ]

   year gender   P
1: 2001   male 0.5
2: 2001 female 1.0
3: 2002   male 0.0
4: 2002 female 0.5
5: 2003   male 0.5
6: 2003 female 0.0
7: 2004   male 0.0
8: 2004 female 0.5

Answer 2

类似的东西？

x <- data.frame(year=rep(2001:2004, each=4), gender=rep(c("male", "female"), 8), union=sample(c("yes", "no"), 16, rep=T))
ddply(x, .(year, gender), summarize, P=mean(union=="yes"))