合并具有相同列的熊猫数据框

Question

I'm trying to merge two data frames, one containing details of the win odds for a horse race and one with the place odds. They share some of the same column names. I am currently getting duplicates on the horse's names, with odds that I don't recognize. I think the problem is occurring because some races don't have a place market, only a win market so it's confusing things. Below is an example of the winning table on the left, place on the right.

Time   Horse      Odds   Result     Time   Horse      Odds_P Result_P     
13:55  Go faster  5.0    1          13:55  Go faster  5.0    1
14:10  Slow down  4.0    0

I want to just be able to add the Odds_P and Result_P for going faster on to the end of the win data frame and drop the entry that has no corresponding Place market.

I've tried concat, join and merge, all of which present me with me some duplicates of horse names, with odds that I don't recognize.

Any help would be greatly appreciated

Answer 1

If I understand you correctly, your odds_p dataframe looks like:

    Time      Horse  Odds  Result
0  13.55  Go faster   5.0       1
1  14:10  Slow down   4.0       0

And result_p looks like:

    Time      Horse  Odds_P  Result_P
0  13.55  Go faster     5.0         1

I will rename the last two columns from odds_p dataframe to Odds_P and Result_P:

odds_p.rename(columns = {'Odds':'Odds_P', 'Result':'Result_P'}, inplace = True)

And now merge both using a RIGHT join:

final_p = pd.merge(odds_p, result_p, on = ['Time', 'Horse', 'Odds_P', 'Result_P'], how = 'right')

Your final output will look like:

    Time      Horse  Odds_P  Result_P
0  13.55  Go faster     5.0         1