COSC 1210 · CS I (Python) · Augustana University

Interactive Companions

Play with the ideas before — or after — you meet them in class. Each one is self-contained, with its own dark-mode toggle, so you can jump in wherever you're reading.
§1 Recursion
1
Recursion Stepper: Watch the Stack
Step through countdown, countdown_back and the star triangles line by line — frames pile up to the base case and unwind, and you see which prints happen on the way down and which on the way back up.
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§2 Plotting
1
GapMinder in Motion: 55 Years of World Development
The lecture's bubble chart — life expectancy against GDP per capita, sized by population, colored by continent — animated from 1952 to 2007. Follow countries, predict-then-play five stories, and read the matplotlib code for every frame.
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§3 Iteration and search
1
Keyword Scanner: Linear Search, One Line at a Time
Step through find_keyword as it reads keywords.txt and tests each word against your sentence. See why "not found" costs the most, why the first keyword in the file wins, and how in finds "mother" in "smothered".
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§4 Strings and patterns
1
Normalize Pipeline: One Link at a Time
Run a sentence through lower(), replace and strip link by link. Reorder, remove or add links and watch which "I am" sentences ELIZA can still answer.
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2
Pattern Lab: One Pattern, Many Sentences
Type a regular expression and see at once which sentences match, what group() and group(1) return, and what re.sub makes of them. Every special character from class: | ^ $ ? . * ( ) \b.
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§5 More to come
more companions coming as the course gets built out

Built to accompany COSC 1210 (CS I, Python). Each page computes everything live in the browser — nothing here is a canned animation.