从数据帧中采样行并保存未选择的行

Question

我正在试图从数据框中随机选择行;但是，我也需要未经选择的。我按照以下步骤进行了

#grades is data with size 100
half-grades = grades[sample(nrow(grades), 50), ]

如何保存未选择的？

Answer 1

假设您正在寻找甚至50％的分割，代码如下：

library(caTools)
split = sample.split(grades,SplitRatio=0.5)
half-grades1 = subset(grades, split == TRUE)
half-grades2 = subset(grades, split == FALSE)

Answer 2

使用caret::createDataPartition()可轻松完成此操作。

library(caret)
theIndex <- createDataPartition(grades, p = .50,list=FALSE)
sampled <- grades[theIndex,]
notSampled <- grades[-theIndex,]

Answer 3

set.seed(1234)
half-grades=grades[-(sample(nrow(grades), 50)), ]