Keeping only the first observation

[Maxwell Agisu]

Dear Stata Users,

I have a small challenge. I have enormous data with repeating information. I would like to keep only the first row per ID. Here is sample data:

* Example generated by -dataex-. To install: ssc install dataex
clear
input int ID
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
4
4
4
4
4
4
5
5
5
5
5
5
6
6
6
6
6
6
6
6
7
7
end

In this case, I would like to have only one row per ID, in the end, I would like to only have seven rows. Thanks for your help!

[Carlo Lazzaro]

Maxwell:
you may want to try:

bysort ID: keep if _n==1

As usual, remember to save your original dataset beforehand.

[Maxwell Agisu]

Thanks a lot Carlo for your support!