Learn data analysis (pandas)
Short lessons written around the screening tests employers use. Read one, then take the test.
Selecting rows and columns with loc, iloc and filtersHow loc and iloc differ, why slice ends behave differently, and how to write combined filters that do not break.Lesson 1
Summarising and combining data with groupby, merge and pivot_tableHow to aggregate by group, join two tables without losing or duplicating rows, and reshape results with pivot_table.Lesson 2
Missing values and data types: isna, fillna, dropna and conversionsHow to find and handle NaN, convert text columns to numbers and dates, and avoid the type mistakes that make totals silently wrong.Lesson 3
Transforming columns: apply, map, str methods and avoiding slow loopsHow to create and change columns with vectorised operations and .str methods, and when apply and map are the right tool.Lesson 4
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