Friend requests i overall acceptance rate

# Table: FriendRequest
# 
# +----------------+---------+
# | Column Name    | Type    |
# +----------------+---------+
# | sender_id      | int     |
# | send_to_id     | int     |
# | request_date   | date    |
# +----------------+---------+
# This table may contain duplicates (In other words, there is no primary key for this table in SQL).
# This table contains the ID of the user who sent the request, the ID of the user who received the request, and the date of the request.
# 
#  
# 
# Table: RequestAccepted
# 
# +----------------+---------+
# | Column Name    | Type    |
# +----------------+---------+
# | requester_id   | int     |
# | accepter_id    | int     |
# | accept_date    | date    |
# +----------------+---------+
# This table may contain duplicates (In other words, there is no primary key for this table in SQL).
# This table contains the ID of the user who sent the request, the ID of the user who received the request, and the date when the request was accepted.
# 
#  
# 
# Find the overall acceptance rate of requests, which is the number of acceptance divided by the number of requests. Return the answer rounded to 2 decimals places.
# 
# Note that:
# 
# The accepted requests are not necessarily from the table friend_request. In this case, Count the total accepted requests (no matter whether they are in the original requests), and divide it by the number of requests to get the acceptance rate.
# 
# It is possible that a sender sends multiple requests to the same receiver, and a request could be accepted more than once. In this case, the ‘duplicated’ requests or acceptances are only counted once.
# 
# If there are no requests at all, you should return 0.00 as the accept_rate.
# 
# The result format is in the following example.
#
# Example 1:
# Input:
# FriendRequest table:
# +-----------+------------+--------------+
# | sender_id | send_to_id | request_date |
# +-----------+------------+--------------+
# | 1         | 2          | 2016/06/01   |
# | 1         | 3          | 2016/06/01   |
# | 1         | 4          | 2016/06/01   |
# | 2         | 3          | 2016/06/02   |
# | 3         | 4          | 2016/06/09   |
# +-----------+------------+--------------+
# RequestAccepted table:
# +--------------+-------------+-------------+
# | requester_id | accepter_id | accept_date |
# +--------------+-------------+-------------+
# | 1            | 2           | 2016/06/03  |
# | 1            | 3           | 2016/06/08  |
# | 2            | 3           | 2016/06/08  |
# | 3            | 4           | 2016/06/09  |
# | 3            | 4           | 2016/06/10  |
# +--------------+-------------+-------------+
# Output:
# +-------------+
# | accept_rate |
# +-------------+
# | 0.8         |
# +-------------+
# Explanation:
# There are 4 unique accepted requests, and there are 5 requests in total. So the rate is 0.80.

import pandas as pd

def acceptance_rate(friend_request: pd.DataFrame, request_accepted: pd.DataFrame) -> pd.DataFrame:
  total_requests = friend_request.drop_duplicates(subset=['sender_id', 'send_to_id']).shape[0]
  total_accepted = request_accepted.drop_duplicates(subset=['requester_id', 'accepter_id']).shape[0]
  rate = round(total_accepted / total_requests, 2) if total_requests > 0 else 0.00
  return pd.DataFrame({'accept_rate': [rate]})