Sepcification

Since most Python codes will use the pandas and numpy packages, any Python code in this article imports the following packages at the beginning by default:

import pandas as pd
import numpy as np

Contents

1 Data object

1.1 Simple set
1.2 Structured data

2 Loop function

2.1 Current value reference
2.2 Using variables
2.3 Sequence number reference
2.4 Adjacent reference
2.5 Loop to generate and execute

3 Grouping operations

3.1 Equivalence grouping
3.2 Non-equivalence grouping
3.3 Ordered grouping
3.4 Inverse grouping

4 Aggregation operations

4.1 Basic aggregation
4.2 Selection as aggregation
4.3 Set aggregation
4.4 Group & aggregate

5 Iterative operations

5.1 Simple iterative operations
5.2 Early terminated iterative operation
5.3 Iteration in groups

6 Position and select

6.1 Positioning operations
6.2 Selection operation
6.3 Positioning calculation

7 Sort and transpose

7.1 Sort a sequence

7.2 Sort the structured data

7.3 Rank a sequence

7.4 Rank the structured data

7.5 Transpose

8 Join operations

8.1 Foreign key association

8.2 Primary key association

8.3 Mixed association

9 Comprehensive examples

9.1 If a user does not take any action within 10 minutes or does not log in within 5 minutes after logging out, the session is considered over. Calculate the number of sessions for each user

9.2 Count the player who scores 3 times in a row within 1 minute

9.3 Calculate the number of users who are active for three consecutive days in every 7 days

9.4 Calculate the next-day retention rate of new users per day

9.5 Calculate the increase of stock price on the day when it is higher than those on the previous and next 5 days