📅  最后修改于: 2022-03-11 14:51:59.695000             🧑  作者: Mango
dataset <- data.frame(continuous = rnorm(n = 10),
binary = sample(x = 0:1, size = 10, replace = TRUE))
dataset
#> continuous binary
#> 1 -0.01978487 0
#> 2 -1.14185292 0
#> 3 0.20931787 0
#> 4 -0.63720730 0
#> 5 1.07750407 1
#> 6 -1.59274225 0
#> 7 -0.48722740 1
#> 8 -0.64151044 0
#> 9 -0.64111755 0
#> 10 0.99598287 1
# your method
mean(dataset[dataset$binary == 1, 1])
#> [1] 0.5287532
mean(dataset[dataset$binary == 0, 1])
#> [1] -0.6378425
# using by
by(data = dataset$continuous, INDICES = dataset$binary, FUN = mean)
#> dataset$binary: 0
#> [1] -0.6378425
#> --------------------------------------------------------
#> dataset$binary: 1
#> [1] 0.5287532