# pyuvdata
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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 for interferometer data
* uvfits -> miriad (aipy)
* miriad (aipy) -> uvfits
* FHD -> uvfits
* FHD -> miriad (aipy)
## File formats for calibration data
* calfits (a new format defined in pyuvdata, detailed memo coming soon). Note that this format was recently defined and may change in coming versions, based on user needs. Consider it to be in a beta version, but we will strive to make future versions backwards compatible with the current format.
## 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
* expand support for calibration solutions: support other formats beyond FITS
For details see the [issue log](https://github.com/HERA-Team/pyuvdata/issues).
## Community Guidelines
Contributions to this package to add new file formats or address any of the
issues in the [issue log](https://github.com/HERA-Team/pyuvdata/issues) are very welcome.
Please submit improvements as pull requests against the repo after verifying that
the existing tests pass and any new code is well covered by unit tests.
Bug reports or feature requests are also very welcome, please add them to the
issue log after verifying that the issue does not already exist.
Comments on existing issues are also 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
* aipy
## Install pyuvdata
For simple installation, the latest stable version is available via pip using ```pip install pyuvdata```
### Optionally install the development version
For the development version, clone the repository using
```git clone https://github.com/HERA-Team/pyuvdata.git```
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 not to 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 pyuvdata```.
# 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 primary calibration interface is via the
UVCal object. The attributes of the UVData and UVCal objects are
described in the uvdata_parameters and uvcal_parameters descriptions at https://pyuvdata.readthedocs.io or [here](https://github.com/HERA-Team/pyuvdata/blob/master/docs).
