The notebook index
Earlier notes
Earlier reference notes remain available at their existing addresses. The current blog concentrates on programming languages, protocols and self-hosted software.
310 notes.
- Could You Build a CSV Unit Normalizer?
Normalize selected temperature columns while retaining original values, units, and enough metadata to reverse or audit the conversion.
- How Would You Create a Public API Health Check?
A small health-check client can report the HTTP response, elapsed time, media type, and whether the body parses as expected.
- Can a Script Find Duplicate Stop Identifiers?
A focused table scan can detect repeated stop IDs and report every affected row without altering the feed.
- How Can You Build a Sensor Gap Reporter?
Compare ordered observation times with an expected cadence and report intervals that exceed a configurable threshold.
- Could You Make a Static Dashboard from a JSON File?
A static page can present a compact reading with its source, unit, freshness, and a direct path to the raw data.
- How Would You Create a Transit Calendar Exercise?
Practice deriving active service IDs for a date by evaluating weekday ranges and then applying date-specific exceptions.
- Can You Build a Tiny Protocol Message Validator?
A lightweight validator can check a message against an explicit schema and return actionable, field-specific diagnostics.
- How Could a CLI Compare Two Data Snapshots?
Compare two snapshots by stable identifier to report added, removed, and changed records with enough detail to investigate each difference.
- How Would You Make a Time-Zone Display Demo?
A small display demo can render one instant in UTC and a selected local zone while showing explicit offsets and the conversion assumptions.
- Can You Create a Data Dictionary Generator?
A schema-to-reference generator can turn field names, types, and notes into a consistent page that helps readers understand a dataset.
- How Could You Build a CSV Export Round-Trip Check?
A round-trip check exports representative records, parses the resulting CSV, and compares both field order and values to catch serialization errors.
- Can a Script Flag Repeated Sensor Readings?
A conservative detector can identify suspicious runs of identical sensor values while preserving every reading for review.
- How Would You Make a Feed Version Notifier?
A small notifier compares a feed’s published identity with a stored prior identity and reports a change without confusing failures with updates.
- Could You Build a Small Dashboard Coverage Map?
A coverage map plots configured station locations and states clearly when those locations and their underlying data were last updated.
- How Can You Make a Command-Line JSON Error Reporter?
A clear JSON error reporter validates response shape and turns structured failures into concise, actionable terminal output.
- Could You Create a GTFS Stop-Time Browser?
A stop-time browser joins a selected trip to its ordered stop events while preserving GTFS service-day times, including values beyond midnight.
- How Would You Build a Data Freshness Report?
A freshness report summarizes observation and retrieval times separately so readers can see when data was measured and when it was obtained.
- Can You Write a Minimal Activity Deduplicator?
A minimal deduplicator records stable activity identifiers and treats repeated delivery as an expected retry while keeping processing safe.
- How Could You Make a Sensor Unit Conversion Page?
A trustworthy conversion page displays the formula, input unit, output unit, and rounding policy beside each calculated reading.
- Can You Build a Schedule Feed Archive Checker?
An archive checker verifies that a schedule archive can be read and contains expected GTFS files with sensible names before deeper validation.
- How Would You Create a Small Historical Data Plot?
A historical plot should make timestamps, units, and missing intervals visible instead of connecting observations in a way that implies unobserved data.
- Could You Make a Public Data License Index?
A public-data license index records each source’s stated reuse terms, the page supporting them, and the date those terms were checked.
- Can You Build a Feed Field Diff Tool?
A field diff tool compares table headers from two feed versions and reports additions, removals, and ordering changes without conflating them.
- How Could You Create a Dashboard No-Data Demo?
Small local fixtures can exercise empty, stale, unavailable, and valid dashboard states without depending on live services.
- What Would a Minimal Reproducible Data Pipeline Include?
A reproducible pipeline preserves a sample, validates its structure, transforms explicitly selected fields, and records which source version produced the result.
- Designing Retry Policies for Public Information Fetchers
A robust fetcher separates retryable failures from permanent ones, uses bounded backoff, and keeps the last successful result visible with its age and provenance.
- How Should an Outage Feed Consumer Handle Duplicate Updates?
A consumer should define event identity, make processing idempotent, and retain enough state to recover safely when updates arrive more than once.
- A Field Guide to Monitoring a Public Data Import Job
Monitor an unattended importer with a compact record of fetch time, parsing outcome, row counts, and safe failure details that help establish whether its data is trustworthy.
- Writing a Runbook for Intermittent Public Data Feeds
A useful runbook gives operators a short sequence for checking connectivity, freshness, response validity, and safe recovery while preserving evidence for follow-up.
- Modeling a Transit Itinerary as a Sequence of Events
Represent a transit journey as ordered events with explicit locations, times, and legs, then validate invariants that expose impossible or ambiguous trip plans.