由两个因子变量子集

Question

考虑到两个因素（fac1、fac2）之间的相互作用，我想聚合我的数据集并为此应用一个函数。例如，考虑

给出的数据集

set.seed(1)
test <- data.frame(fac1 = sample(c("A", "B", "C"), 30, rep = T), 
                   fac2 = sample(c("a", "b"), 30, rep = T), 
                   value = runif(30))

对于 fac1 == "A" 和 "fac2 == a"，我们有五个值，我想按分钟汇总。我用蛮力试过这种方法

min(test[test$fac1 == "A" & test$fac2 == "a", ]$value)

Answer 1

您提到 aggregate，这将在这里起作用。

aggregate(test$value, test[,1:2], min)
  fac1 fac2          x
1    A    a 0.32535215
2    B    a 0.14330438
3    C    a 0.33239467
4    A    b 0.33907294
5    B    b 0.08424691
6    C    b 0.24548851

Answer 2

这是一个tidyverse备选方案

test %>% group_by(fac1, fac2) %>% summarise(x = min(value))
## A tibble: 6 x 3
## Groups:   fac1 [?]
#  fac1  fac2       x
#  <fct> <fct>  <dbl>
#1 A     a     0.325
#2 A     b     0.339
#3 B     a     0.143
#4 B     b     0.0842
#5 C     a     0.332
#6 C     b     0.245

由两个因子变量子集

Subset by two factors variables

aggregate

r

factors