Delete Id from dataframe if variable of id contains particular value

General Usage
5

Ah that’s the bit I didn’t understand, you want something like

julia> df[transform(groupby(df, :id), :v1 => maximum).v1_maximum .< 9, :]
6×2 DataFrame
 Row │ id     v1    
     │ Int64  Int64 
─────┼──────────────
   1 │     1      1
   2 │     2      2
   3 │     1      4
   4 │     2      5
   5 │     1      7
   6 │     2      8
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