Frequently Asked Questions¶
Is your library mature for production code?¶
No. The API is not always as clever as I wish it would, and it will probably change in the future. It is quite well tested though, at least for the cases I encounter in my daily work.
What others tools should I know about?¶
The python atmopsheric sciences community is a bit spread between iris and xarray for N-Dimensional data handling (I picked the later for it’s strong interaction with pandas). Several great libraries are available to meteorologists and climatologists, for example MetPy, windspharm, xgcm, and all the ones I forgot to mention.
But then, why developing Salem?¶
As an atmospheric scientist, I hate to have to take care about projections and maps. Salem was created to hide all these concerns. By the time I started, it seemed a good idea to provide map transformation tools without depending on GDAL (thanks to conda-forge GDAL is now much easier to install). It is still possible to do reprojection work in Salem using scipy and pyproj alone. It is al done in python and on memory, so don’t expect miracles on that side.
Furthermore, I use the atmospheric model WRF quite often in my work. Its output files are absolutely not compliant with the CF conventions. To my knowledge, there is no tool to plot and manipulate WRF data with Python, and Salem will be further developed with this model in mind.
Why aren’t you using Xarray/Cartopy for your maps?¶
This is actually a good question, and I think that there are no obstacle for Salem to use it’s geolocation information to plot gridded data on cartopy’s maps. I never really got to understand how cartopy really works, but I’m sure that salem’s Grid object would be able to provide the right info to cartopy with a little bit of coding. Contributions welcome!
On the other hand I kind of like how Salem’s Map output looks, and I find it nice and easy to use. But that, of course, might not be your opinion. Other advantages of Salem’s Maps are their persistence (usefull if you want to plot data on the same map several times), their internal optimisations based on disk cache, and the ability to add lon-lat orientation grids to virtually any map projection.
What’s this ”.salem_cache” directory in my home folder?¶
At the first import, Salem will create a hidden directory called .salem_cache in your home folder. It will be used to download Salem’s demo files and standard shapefiles. This directory is also used by joblib to store the result of slow operations such as reading and transforming shapefiles, or downloading google maps from the internet. The cache should not become too large, but if it does: simply delete it.