# pyuvdata
pyuvdata defines a pythonic interface to interferometric data sets. Currently pyuvdata supports reading and writing of miriad and uvfits files and reading of FHD ([Fast Holographic Deconvolution](https://github.com/EoRImaging/FHD)) visibility save files.   


# Motivation
The three main goals are:

1. To provide a high quality, well documented path to convert between data formats
2. Support the direct use of datasets from python with minimal software
3. Provide precise data definition via both human readable code and high quality online documentation

# Package Details
## Tested File Paths
* uvfits -> miriad (aipy)
* miriad (aipy) -> uvfits
* FHD -> uvfits
* FHD -> miriad

## File standards
* miriad is supported for aipy-style analysis, further testing is required for use in the miriad package
* uvfits conforms to AIPS memo 117 (as of May 2015).  It is tested against FHD, CASA, and AIPS. However AIPS is limited to <80 antennas and CASA imaging does not seem to support >255 antennas.
* FHD (read-only support, tested against MWA and PAPER data)

## Known Issues and Planned Improvements
* different multiple spectral windows or multiple sources are not currently supported
* testing against miriad package
* replacing AIPY and pyephem with astropy+NOVAS for time and phase calculations
* support for direct reading and writing of Measurement Sets

For details see the [issue log](https://github.com/HERA-Team/pyuvdata/issues). Contributions are welcome!



# History
pyuvdata was originally developed in the low frequency 21cm community to support the development of calibration and foreground subtraction pipelines. Particular focus has been paid to supporting drift and phased array modes.




# Installation
## Dependencies
First install dependencies. The numpy and astropy versions are important, so be sure to make sure these are up to date before you install.
* numpy >= 1.10
* scipy
* astropy >= 1.2
* pyephem
* pyfits
* aipy

## Install pyuvdata
Download the latest release here github.com/HERA-Team/pyuvdata/release1.0

Navigate into the directory and run
`python setup.py install` Note that this will automatically install all dependencies.  If you use anaconda or another package manager you might prefer to do not do this.

To install without dependencies, run
`python setup.py install --no-dependencies`

## Tests
Requires installation of `nose` package.
From the source pyuvdata directory run `nosetests`.


# API
The primary interface to data from python is via the UVData object. It provides
import and export functionality to all supported file formats (UVFITS, Miriad, FHD)
and can be interacted with directly. The attributes of the UVData object are
described in the parameters description at https://pyuvdata.readthedocs.io or [here](https://github.com/HERA-Team/pyuvdata/blob/master/docs/parameters.rst).