mickolaua / pyslalib

f2py and numpy wrappers of the fortran version of the astro library SLALIB

pySLALIB v1.1.0 (Jan 2023)

pySLALIB provides interface for the Fortran version of P.T. Wallace's SLALIB positional astronomy library via f2py-generated (and hand-tweaked to eliminate unnecessary function/subroutine arguments) wrappers. SLALIB used to be hosted by the STARLINK site, although that service has been suspended. The version of SLALIB included here is 2.5-4 (with several additional tweaks) and is released under the GPL.

The python wrappers cover every function in SLALIB and a comprehensive set of unit tests are available in the test/ directory. The only external dependency is numpy (http://numpy.scipy.org). These wrappers are not related to the older (and apparently abandoned) pySLALIB that was once available on the Web (and which depended on Numeric as opposed to numpy).

Note: this version supports Windows (user must install mingw64-toolkit before building pySLALIB).

Build

Note: if not stated, commands are executed from repository directory.

• Windows

  Since version 1.1.0 building the pySLALIB is supported under Windows. This is available due to new build system meson-python via MinGW64 toolchain set of GCC compilers and libraries.

  Prerequisites

  • msys2 (https://www.msys2.org/)
  • mingw64-w64-toolchain (pacman -Syu mingw64-w64-toolchain from MSYS2 terminal)

  Steps

  1. Add E:\Programs\msys64\usr\bin (example path to /usr/bin directory in MSYS2 installation) to the PATH (powershell example):

     $Env:PATH="E:\Programs\msys64\usr\bin;" + $PATH
     

  2. Install python dependencies:

     pip install -r requirements.txt
     

  3. Run build:

     python -m build -w -n .
     

• Linux (Ubuntu 2x.04)

  pySLALIB natevily supports Linux.

  Prerequisites

  • python3-pip
  • build-essential
  • gfortran

  Steps

  1. Install system dependencies:

     sudo apt install build-essential python3-pip gfortran
     

  2. Install python dependencies:

     pip install -r requirements.txt
     

  3. Run build:

     python -m build -w -n .
     

All built wheels (.whl files) will be placed to the directory dist under current repository if parameter -o is not provided in #3 step. Note, tags are already passed all tests before uploading.

Installation

Most users will only need to do:

pip install <name-of-the-pyslalib-wheel>.whl

to generate the wrappers, build, and install the package. This method is preferrable since binary distributions are already uploaded for platforms Windows X86-64 and Linux X86-64. Otherwise one should build the packages before proceeding to the installation (see previous section).

Once pySLALIB is installed, you can run the unittests via:

  > python test/test_slalib.py

Example Usage (using IPython)

In [1]: import pyslalib as slalib

In [2]: slalib.sla_veri()
Out[2]: 2005004

In [3]: slalib.sla_caldj(1999, 12, 31)
Out[3]: (51543.0, 0)

In [4]: slalib.sla_etrms(1976.9)
Out[4]: array([ -1.62161710e-06,  -3.31007009e-07,  -1.43529663e-07])

In [5]: slalib.sla_fk45z(1.234, -0.123, 1984)
Out[5]: (1.2446165107316911, -0.12141858395865548)

In [6]: slalib.sla_dafin("-00 03 34.6", 1)
Out[6]: (12, -0.0010404101596610642, 0)

In [7]: slalib.sla_obs(0, "GBT")
Out[7]:
('GBT',
 'Green Bank Telescope                    ',
 1.3934679949996727,
 0.67078450520692623,
 880.0)

You can print the original Fortran doc strings using something like:

In [1]: from pyslalib import sla_caldj

In [2]: sla_caldj?
"""
*     - - - - - -
*      C A L D J
*     - - - - - -
*
*  Gregorian Calendar to Modified Julian Date
*
*  (Includes century default feature:  use sla_CLDJ for years
*   before 100AD.)
*
*  Given:
*     IY,IM,ID     int    year, month, day in Gregorian calendar
*
...

If you find any problems, please sent message to original developer Scott M. Ransom [e-mail] or this version contributor Nicolai S. Pankov [e-mail]