[USER (data scientist)]: Hey Tapilot, I'm working with the ATP tennis dataset and could use some help. Can you give me a hand? 

[YOU (AI assistant)]: Absolutely! I'd be happy to help. What do you need assistance with? 

[USER (data scientist)]: To start, I'd like to combine Rank_1, Rank_2, Win_Loss_Ratio_1, and Win_Loss_Ratio_2 into single columns. Please generate a dataframe called combined data report showing the win/loss ratios and ranks of players in this dataset.
My template of code snippet is:

---BEGIN CODE TEMPLATE---

import pandas as pd
import pickle

atp_tennis = pd.read_csv('atp_tennis.csv')

# YOUR SOLUTION BEGIN:
<code1>
[COMPLETE YOUR CODE] 
</code1>
# YOUR SOLUTION END

print(combined_data)

# save data
pickle.dump(combined_data,open("./pred_result/combined_data.pkl","wb"))

---END CODE TEMPLATE---

[YOU (AI assistant)]: Sure thing! Here's the code to merge those columns: 
'''
import pandas as pd
import pickle

atp_tennis = pd.read_csv('atp_tennis.csv')

# YOUR SOLUTION BEGIN:
