R - 从每组值的数据集中选择一个样本

Question

我有一个如下所示的数据集：

string_1,score,group
"sdfsd",0.546,0.5
"sdfsd",0.53,0.5
"sdfsd",0.52,0.5
"dgfbx",0.43,0.4
"dsgfgsd",0.48,0.4
"dsgfgsd",0.42,0.4
"dsgfgsd",0.84,0.8
"dsgfgsd",0.83,0.8
"dsgfgsd",0.82,0.8

我想从每组中抽样。含义 - 我想从每组值中随机取 2 行：0.4,0.5,0.8（组字段）

最简单的方法是什么？

谢谢

Answer 1

你可以考虑做这样的事情。它按组拆分您的数据，并 returns 采样行。

set.seed(1)
res <- do.call(rbind,lapply(split(dat,dat$group),function(x){x[sample(nrow(x),2),]}))
> res
      string_1 score group
0.4.4    dgfbx  0.43   0.4
0.4.6  dsgfgsd  0.42   0.4
0.5.2    sdfsd  0.53   0.5
0.5.3    sdfsd  0.52   0.5
0.8.7  dsgfgsd  0.84   0.8
0.8.8  dsgfgsd  0.83   0.8

R - 从每组值的数据集中选择一个样本

R - choose a sample from a data set from each group of values

r

sample