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analysis.py

def solve(sales):
    m = sales['date'].dt.strftime('%Y-%m')
    rev = sales.groupby(m)['revenue'].sum()
    return rev.pct_change() * 100

Solved. Month-over-month growth

SQL

226 problems

Joins, subqueries and CTEs
Window functions and recursion
A 10-table store and school database

Python

226 problems

Strings, lists and dictionaries
Classes, recursion and sorting
Dynamic programming and graphs

Data Analysis

800 problems

pandas: filter, group, pivot, merge
Time series, cleaning and statistics
Business metrics and SQL for analysts

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