gribextractor CLI — Usage & Examples 📋

This file documents the common cli usage and examples for extracting timeseries from GRIB2 files.

Flags

• --probe <lon> <lat> <file.grib2> — probe a single file and print available keys and values at the point
• --timeseries <param[,param,...]> — request one or multiple timeseries parameters (e.g., 2t, tp, msl)
• --init YYYYmmddHH — initial time used to match files and to compute timestamps
• --lon <lon> --lat <lat> — probe location
• --data-dir <dir> — directory containing GRIB2 files
• --out-json <file> — write results in JSON format
• --out-csv <file> — write results in CSV format
• --verbose / -v — print debug information

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Important output behavior ✅

• --out-json <file> now writes only JSON and will not implicitly create a CSV file.
• --out-csv <file> explicitly creates CSV output. CSV is generated from the same aligned timeseries data as JSON so the values are consistent between formats.
• tps values are included only when the tp parameter is requested (either alone or as part of a comma-separated list). When present:
  • JSON: each row will have a tps field (in mm) computed from cumulative tp values (first entry = 0.0, second = first cumulative, subsequent = differences).
  • CSV: an extra tps column is appended (same values as JSON per-row tps).

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Examples

• Probe a single file:

cargo run --bin gribextractor -- --probe 88.363 12.962 ./gribfiles/2t_2025122900_000-024.grib2

• Single-parameter timeseries printed to console:

cargo run --bin gribextractor -- --timeseries 2t --init 2025122900 --lon 88.363 --lat 12.962 --data-dir gribfiles

• Generate JSON only:

cargo run --bin gribextractor -- --timeseries 2t,tp --init 2025122900 --lon 88.363 --lat 12.962 --data-dir gribfiles --out-json out.json

The produced out.json will include tps fields because tp was requested.

• Generate CSV only:

cargo run --bin gribextractor -- --timeseries 2t,tp,msl,10u,10v --init 2025122900 --lon 113.363 --lat 22.962 --data-dir D:\work\realtimeforecast\2025122900 --out-csv out.csv

The produced out.csv will include an extra tps column when tp is in the requested list.

• Generate both JSON and CSV:

cargo run --bin gribextractor -- --timeseries 2t,tp --init 2025122900 --lon 88.363 --lat 12.962 --data-dir gribfiles --out-json out.json --out-csv out.csv

• Request a non-tp param (no tps should be present):

cargo run --bin gribextractor -- --timeseries 2t --init 2025122900 --lon 88.363 --lat 12.962 --data-dir gribfiles --out-json out2.json

out2.json will not contain tps fields because tp was not requested.

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Notes & Developer info 🔧

• The timeseries alignment and tps computation have been factored into a reusable internal module gribextractor::timeseries::build_aligned_timeseries so CSV and JSON outputs are generated from the same data source (JSON is used as the authoritative format).
• If you want me to add examples showing how to read the JSON output programmatically or add more documentation about the internal API, I can add that too.

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Happy data extracting! 🚀