R 如何根据连续变量将数据分成随机相等的组？

我想根据我的变量x（在-3.5和3.5之间连续）随机分成两组（每组6名参与者）进行实验

各组的形成方式应确保形成后，对各组进行比较的t检验不显著（例如，第1组的x均值为2.05，第2组的x均值为2.15）

因此，我还希望在数据集中添加一列，基本上是为每个参与者指定group1或group2，并保留所有其他列

到目前为止，我已经使用了包

Dplyr

，但还没有找到解决方案

这是一个可复制的样品：

ID <- c("1","2","3","4","5","6","7","8","9","10","11","12","13","14")    
x <- c("0.65","1.25","1.55","1.80","1.95","2.05","2.25","2.30","2.45","2.6","2.85","2.9","3.00","3.05")    
age <-    c("36","26","87","27","24","50","27","36","46","44","33","38","47","41")    
gender <- c("M","M","F","M","F","F","M","F","M","F","F","M","F","F")

df <- data.frame(ID, x, age, gender)

---

ID随机抽样的要点是在不施加与
x
值相关的选择要求的情况下获得该结果。随机抽样的要点是在不施加与
x
值相关的选择要求的情况下获得该结果。