假设我有以下(虚拟)df:
df <- data.frame(conference = c('East', 'East', 'East', 'West', 'West', 'East'),
team = c('A', 'A', 'A', 'B', 'B', 'C'),
points = c(11, 8, 10, 6, 6, 5),
rebounds = c(7, 7, 6, 9, 12, 8))
我想对得分和篮板一栏做一些计算.在R基地,我可以做像这样的事情
a_val <- sum(df$points[which(df$team == "A")]) /
sum(df$rebounds[which(df$team == "A")])
b_val <- sum(df$points[which(df$team == "B" & df$rebounds >= 7)]) /
sum(df$rebounds[which(df$team == "B" & df$rebounds >= 7)])
在整齐的诗句中,使这些操作更有效率的which()
相当于什么?