> df <- data_frame(name = c("A","B","C","D"), count = c(1,3,5,2), avg = c(100,50,20,10))
> df
# A tibble: 4 × 3
   name count   avg
  <chr> <dbl> <dbl>
1     A     1   100
2     B     3    50
3     C     5    20
4     D     2    10

10 10 20 20 20 20 20 50 50 50 100

> median(df$avg)
[1] 35