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Level 0 / Project 14 - Line Length Summarizer

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Concept This project — Quiz Flashcards Diagram Browser

Estimated time: 30 minutes

Focus

  • loop metrics and summary output

Why this project exists

Measure the length of every line in a file and compute min, max, and average statistics. You will also build a text-based histogram and categorise lines as short, medium, or long -- practising loops, aggregation, and visual output.

Run (copy/paste)

Use <repo-root> as the folder containing this repository's README.md.

cd <repo-root>/projects/level-0/14-line-length-summarizer
python project.py --input data/sample_input.txt
pytest -q

Expected terminal output

=== Line Length Summary ===
  Total lines: 4
  Shortest:    5 chars
  Longest:     64 chars
  Average:     28 chars

  Histogram:
    11 | ######
    64 | ##################################
     5 | ###
4 passed

Expected artifacts

  • data/output.json
  • Passing tests
  • Updated notes.md

Checkpoint: Baseline code runs and all tests pass. Commit your work before continuing.

Alter it (required) — Extension

  1. Add a "median line length" metric to compute_stats().
  2. Add a --threshold flag that customises the short/medium/long category boundaries.
  3. Re-run script and tests.

Break it (required) — Core

  1. Use an empty file -- does compute_stats() crash on min([]) or sum([]) / 0?
  2. Use a file where every line is the same length -- does the histogram still display correctly?
  3. Use a file with one very long line (10,000+ characters) -- does the histogram bar overflow?

Fix it (required) — Core

  1. Add a guard for empty files that returns zero stats without crashing.
  2. Cap histogram bar length to a maximum width (e.g. 50 characters).
  3. Add a test for the empty-file edge case.

Checkpoint: All modifications done, tests still pass. Good time to review your changes.

Explain it (teach-back)

  1. Why does compute_stats() compute min, max, and average but not median?
  2. What does build_histogram() use to scale the bar lengths proportionally?
  3. Why categorise lines as short/medium/long instead of just showing raw lengths?
  4. Where would line length analysis appear in real software (linting, code style checks, log analysis)?

Mastery check

You can move on when you can: - run baseline without docs, - explain one core function line-by-line, - break and recover in one session, - keep tests passing after your change.

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