I have the following dataset:
ID   age   sugarlevel
123  12      8
456  13      10
789  25      5
...  
I'm trying to use R to split the data depending on the sugar level (>=7, <7)
This should give me 2 groups:
group 1:
ID  age  sugarlevel
123  12     8
456  13      10
group 2:
ID  age  sugarlevel
789  25      5