Q:

remove the first row for each group

suppose I have a dataset like this 
df <- data.frame(group = c(rep(1,3),rep(2,2), rep(3,2),rep(4,3),rep(5, 2)), score = c(30, 10, 22, 44, 6, 5, 20, 35, 2, 60, 14,5)) 

   group score
1      1    30
2      1    10
3      1    22
4      2    44
5      2     6
6      3     5
7      3    20
8      4    35
9      4     2
10     4    60
11     5    14
12     5     5

I want to remove the first row for each group, the expected out put should look like this:
   group score
1      1    10
2      1    22
3      2     6
4      3    20
5      4     2
6      4    60
7      5     5

Is there a simple way to do this?

A:

Quite simple with duplicated
df[duplicated(df$group),]

   group score
2      1    10
3      1    22
5      2     6
7      3    20
9      4     2
10     4    60
12     5     5

A:

An option with dplyr is to select rows ignoring 1st row
library(dplyr)
df %>%
  group_by(group) %>%
  slice(2:n())

#  group score
#  <dbl> <dbl>
#1  1.00 10.0 
#2  1.00 22.0 
#3  2.00  6.00
#4  3.00 20.0 
#5  4.00  2.00
#6  4.00 60.0 
#7  5.00  5.00

Another way is shown by @Rich Scriven in now deleted answer 
df %>%
  group_by(group) %>%
  slice(-1)

