I have a data frame called df(this is just example, the real data is big, please consider the computing speed) as following:

```
   name   id     text
    tom    1      a1 
    lucy   2      b1
    john   3      c1
    tick   4      d1
    tom    1      a2 
    lucy   2      b2
    john   3      c2
    tick   4      d2
    tom    1      a3 
    lucy   2      b3
    john   3      c3
    tick   4      d3
    tom    1      a4 
    tick   4      d4
    tom    1      a5 
    lucy   2      b5
    tick   4      d5

```

the dataframe can be grouped by the name(tom, john, lucy, tick). I want to delete the data that the size of each group(by name)is less 5. I mean since the size of name of lucy and john is less 5, I want to delete these data and get the new df(just have tick and tom data), such as.

Could you tell me how to do it,please! Thanks!