Count Events Per User

Given a DataFrame of user events, return the total number of events per user, sorted by user_id ascending.

Schema

df

column	type
user_id	int
event_type	str

Sample Input

user_id	event_type
1	click
2	view
1	purchase
3	click
2	click
3	view

Expected Output

user_id	event_count
1	2
2	2
3	2

Explanation

Each user appears exactly once in the output with a count of how many rows they had in the input.