What is PYACS?

PYACS is a collection of Python modules and scripts for analyzing and modeling geodetic data, with a focus on tectonic applications.

It provides tools for handling GNSS solutions, geodetic time series, and velocity fields.

PYACS is designed primarily for researchers working on crustal deformation and tectonics using geodetic observations.

Python ≥ 3.8 (current version tested with Python 3.12)

Documentation

Online documentation:

https://jmnocquet.github.io/pyacs_docs/pyacs

Source code:

https://github.com/JMNocquet/pyacs36

The philosophy of PYACS

Although PYACS includes a few ready-to-use scripts, it is primarily intended as a collection of tools that analysts can use to develop their own applications and workflows.

PYACS is continuously evolving as new capabilities are added depending on the needs of users.

The software is provided as is, without warranty.

PYACS is not intended to replace more comprehensive geodetic processing software. Instead, it aims to enable rapid and robust analysis of geodetic data.

Rapid solutions are obtained by focusing on practical approximations rather than fully propagating the complete variance of the solutions. Robustness is achieved through extensive use of L1-norm estimators, which are less sensitive to outliers.

Main components of PYACS

PYACS includes several main components.

Core libraries

A set of Python modules handling:

  • coordinate transformations

  • time representations

  • least-squares estimators

  • format conversions

GNSS time series generation

The script pyacs_make_time_series.py converts free GNSS solutions (typically in SINEX format) into time series expressed in a consistent reference frame.

Geodetic Time Series module (Gts)

The gts package provides a framework for the analysis of geodetic time series, including:

  • loading time series

  • visualization

  • filtering

  • offset estimation

  • trend estimation

Velocity field analysis

The vel_field module provides tools for analyzing horizontal GNSS velocity fields, including:

  • Euler pole estimation

  • strain-rate analysis

Interactive environment

ipyacs.py provides an interactive environment for working with PYACS through IPython.

Typical workflow

A typical PYACS workflow for GNSS time-series analysis may involve the following steps.

  1. Generate station time series from free GNSS solutions in SINEX format:

    pyacs_make_time_series.py

  2. Load time series and work interactively, for example in a Jupyter notebook environment:

    from pyacs.gts.Sgts import Sgts

ts = Sgts("timeseries_directory")
ts.CODE.plot()
ts.CODE.add_offsets_dates([2016.29, 2018.315]).plot()

dts = ts.gts('detrend')

  3. Export velocity fields and perform Euler pole estimation or strain-rate analysis.