Sort value by predefined list

Question

If I have created a predefined list, say top 3 stocks in the order of ["CAT","AI", "BOC"], how can I get this new dataframe by working from the original dataframe below that will essentially sort_value the ticker column by the order for which the above predefined list is shown? (still chronological order also)

Thanks

     date       price ticker  volume
0  2018-01-01  1.323     AI    2000
1  2018-01-02  1.525     AI    1500
2  2018-01-03  1.045     AI     500
3  2018-01-01  2.110    BOC    3201
4  2018-01-02  2.150    BOC    5200
5  2018-01-03  2.810    BOC    1980
6  2018-01-01  5.199    CAT    2000
7  2018-01-02  4.980    CAT     450
8  2018-01-03  4.990    CAT    3000

Answer 1

One option could be to create an ordered Categorical column, apply argsort on it which returns the correct indices to reorder your data frame:

df.iloc[pd.Categorical(df.ticker, categories=["CAT","AI", "BOC"], ordered=True).argsort()]

#         date  price ticker  volume
#6  2018-01-01  5.199    CAT    2000
#7  2018-01-02  4.980    CAT     450
#8  2018-01-03  4.990    CAT    3000
#0  2018-01-01  1.323     AI    2000
#1  2018-01-02  1.525     AI    1500
#2  2018-01-03  1.045     AI     500
#3  2018-01-01  2.110    BOC    3201
#4  2018-01-02  2.150    BOC    5200
#5  2018-01-03  2.810    BOC    1980