pygnss is a lightweight collection of utilities for GNSS data processing:

• parsers for Hatanaka (CRX) and RINEX formats,
• IONEX (GIM) utilities and exporters,
• small geodetic and ionospheric helpers, and
• a few filtering tools (particle filter, EKF/UKF helpers) used in demos and tests.

This README gives a short overview for users and contributors: installation, development (building the compiled extension), available CLI scripts and examples of the most used APIs.

Stable release from PyPI (no compiled extension required for pure-Python features):

pip install pygnss

Developer / editable install (builds the C extension declared in pyproject.toml). This is the recommended setup when working on the repository locally because some features (Hatanaka/CRX parsing) rely on a compiled extension for speed.

# create and activate a venv
python -m venv .venv
source .venv/bin/activate
# install the package and test/dev extras
python -m pip install --upgrade pip
python -m pip install -e '.[test]'

Notes on the compiled extension

• The extension module pygnss._c_ext is built from the sources listed in pyproject.toml (under [[tool.setuptools.ext-modules]]). Building the package with pip install . or python -m build will compile it. On CI the workflow provided in .github/workflows/python-package.yml creates a virtualenv and runs pip install -e '.[test]' to ensure the entry points and compiled modules are available for tests.

The package declares several console scripts (see pyproject.toml):

• ionex_diff — compare IONEX files or compare an IONEX to NeQuick output
• compute_cdf — utility to compute CDF from data (used by examples)
• rinex_from_file, rinex_to_parquet, merge_rinex_nav — helpers for RINEX conversions

After installing the package into a venv these commands are available on $PATH (from .venv/bin). Tests rely on the entry points being discoverable via PATH in CI, so the workflow prepends .venv/bin to PATH before running tests.

1. Hatanaka (CRX) -> pandas DataFrame

from pygnss import hatanaka

df = hatanaka.to_dataframe('station.crx.gz', station='MYST')
print(df.head())

If the compiled extension is not available the function raises an ImportError with instructions to build/install the package (see "Developer" section).

1. Read and diff IONEX maps (programmatic)

from pygnss import ionex
from pygnss.iono import gim

# load an ionex and collect VTEC maps
handler = gim.GimHandlerArray()
ionex.load('sample.ionex', gim_handler=handler)
print(len(handler.vtec_gims))

With the venv active and the test extras installed the canonical way to run the test-suite is:

# inside the project root with .venv activated
python -m pytest -v

If tests call console scripts (such as ionex_diff) the venv bin directory must be on PATH so subprocesses can find the entry points. The CI workflow prepares the environment accordingly.

• pygnss/hatanaka.py — Hatanaka/CRX parsing wrapper (uses compiled helper)
• pygnss/ionex.py — IONEX loader/writer and CLI glue
• pygnss/filter/ — particle filter, EKF/UKF helpers and demos