R：根据组和不同条件子集数据帧

Question

考虑一个数据框：

data = data.frame(a=c(1,1,1,2,2,3),
              b=c("apples", "oranges", "apples", "apples", "apples", "oranges"),
              c=c(12, 22, 22, 45, 67, 28), 
              d=c("Monday", "Monday", "Monday", "Tuesday", "Wednesday", "Tuesday"),
              out = c(12, 14, 16, 18, 20, 22),
              rate = c(-0.01, -0.02, 0.03, -0.04, 0.07, 0.06))

我希望对数据框进行子集化，以便在水果为苹果时速率为负时保持值，而当水果为橙色时速率为正。即我想要的输出是

data = data.frame(a=c(1,2,3),
              b=c("apples", "apples", "oranges"),
              c=c(12, 45, 28), 
              d=c("Monday", "Tuesday", "Tuesday"),
              out = c(12, 18, 22),
              rate = c(-0.01, -0.04, 0.06))

有办法吗？

Answer 1

我不知道如何处理dplyr。但是，您可以使用subset轻松完成此操作

data = data.frame(a=c(1,1,1,2,2,3),
              b=c("apples", "oranges", "apples", "apples", "apples", "oranges"),
              c=c(12, 22, 22, 45, 67, 28), 
              d=c("Monday", "Monday", "Monday", "Tuesday", "Wednesday", "Tuesday"),
              out = c(12, 14, 16, 18, 20, 22),
              rate = c(-0.01, -0.02, 0.03, -0.04, 0.07, 0.06))

subData <- subset(data, (b == "apples" & rate < 0) | (b == "oranges" & rate > 0))

代码非常简单。它将data子集设置为寻找你的两个约束。在此代码中，&代表and而|代表or。

Answer 2

这是一个dplyr解决方案：

library(dplyr)
data %>% 
  filter((b == "apples" & rate < 0) | (b == "oranges" & rate > 0))

  a       b  c       d out  rate
1 1  apples 12  Monday  12 -0.01
2 2  apples 45 Tuesday  18 -0.04
3 3 oranges 28 Tuesday  22  0.06