Python Lesson 10: pandas — Summaries and Pivot Tables
Summarise data with pandas: groupby with sum and count, several aggregations with agg, pivot_table with totals, top-N with nlargest, monthly summaries, and percentage of…
Read article →Coding
Start-to-finish programming for people who work with data: Python, SQL, Java, R, JavaScript, Rust and PowerShell.
Python Lesson 9: pandas — Cleaning Messy Data
Python Lesson 9: pandas — Cleaning Messy Data
Clean a real-world messy export with pandas: tidy column names, trim and fix case, turn “Rs 1,23,000” into numbers, parse mixed date formats, remove…
Read article →Python Lesson 8: pandas — Reading and Exploring Data
Python Lesson 8: pandas — Reading and Exploring Data
Start with pandas: read CSV and Excel files into a DataFrame, check shape and data types, view rows, add calculated columns, and filter rows…
Read article →Python Lesson 7: Reading and Writing Files
Python Lesson 7: Reading and Writing Files
Read and write CSV files with Python’s standard library: open with a with-block, csv.DictReader, totals with defaultdict, writing a result file, encodings, and file…
Read article →Python Lesson 6: Functions
Python Lesson 6: Functions
Write your own reusable functions with def: parameters, default values, return, docstrings, and practical examples like GST, financial-year labels and grading — Python’s version…
Read article →Python Lesson 5: Loops
Python Lesson 5: Loops
Repeat work with for loops over lists, dictionaries and ranges, count and total inside loops, list comprehensions, while loops, and break/continue — the code…
Read article →Python Lesson 4: Lists and Dictionaries
Python Lesson 4: Lists and Dictionaries
Hold many values with lists (indexing, append, sort, slices) and look things up with dictionaries (keys, get, items) — Python’s versions of a column…
Read article →Python Lesson 3: Decisions With if, elif and else
Python Lesson 3: Decisions With if, elif and else
Make decisions in Python: comparisons, if/elif/else blocks and indentation, and/or/not, one-line conditional expressions, and the IF patterns from Excel translated to Python.
Read article →Python Lesson 2: Variables, Numbers and Text
Python Lesson 2: Variables, Numbers and Text
Store values in variables, use int, float, str and bool, do maths with rounding, format output with f-strings including thousands separators, and convert between…
Read article →Python Lesson 1: Install Python and Run Your First Program
Python Lesson 1: Install Python and Run Your First Program
Install Python on Windows the right way, use VS Code or IDLE, run a script from the terminal, use the interactive prompt, and install…
Read article →JavaScript Lesson 8: Fetch — Getting Data From an API
JavaScript Lesson 8: Fetch — Getting Data From an API
Call web APIs with fetch, async/await, check response status, parse JSON, handle errors and offline cases, and where API keys must never go.
Read article →JavaScript Lesson 7: The DOM — Changing a Web Page
JavaScript Lesson 7: The DOM — Changing a Web Page
Make a page interactive: select elements with getElementById and querySelector, read input values, handle click events, change text and create elements.
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