R：根据组和不同条件对数据框进行子集

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))

我想对数据框进行子集化，以在水果为苹果时为负数而在水果为橙色时为正数时保留值。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

这是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

Answer 2

我不知道如何处理dplyr。但是，您可以使用 subset 轻松做到这一点

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))

代码很简单。它子集data 寻找您的两个约束。在这段代码中，& 代表and，而| 代表or。