R Data.Table随机样本组

Question

DATA = data.table(STUDENT = c(1,1,2,2,2,2,2,3,3,3,3,3,4,
SCORE = c(5,6,8,3,14,5,6,9,0,12,13,14,19))

WANT = data.table(STUDENT = c(1,1,4),
SCORE = c(5,6,19))

我有数据并希望创建 WANT，它随机抽取 2 名学生并包含他们的所有数据。 我以 WANT 为例。

我尝试这个没有成功

WANT = WANT[ , .SD[sample(x = .N, size = 2)], by = STUDENT]

Answer 1

对STUDENT的unique值进行sample并过滤这些STUDENT的所有行，

library(data.table)
set.seed(1357)
DATA[STUDENT %in% sample(unique(STUDENT), 2)]

#   STUDENT SCORE
#1:       1     5
#2:       1     6
#3:       4    19