tobac v1.6.0 released

[William Jones]

Dear tobac users,

We are pleased to announce the release of tobac v1.6.0, which is now available on conda-forge.

This is a major release, the culmination of efforts to shift the basis of tobac from Iris to xarray in line with the majority of the python geosciences ecosystem. This change will streamline further development of tobac, and help carry out the steps planned in the roadmap. I'd like to extend particular thanks to Sean Freeman for his efforts over the past year and a half bringing this release to fruition.

Due to the major changes to the way tobac works under the hood, there are a number of differences that we would like to highlight to users of the new version. We recommend that you use xarray DataArrays for all geospatial data input, rather than iris Cubes. Extensive effort has been made to ensure backward compatibility with iris Cube input, and in general outputs should be identical. One key difference is that, by default, the column names for coordinates in feature detection output will use the variable name for xarray input rather than the standard name for iris input, to reflect the way that variables are displayed in each data type. This change also avoids issues that can arise when multiple coordinates have the same standard name. This behaviour can be controlled using the "use_standard_names" parameter in feature detection if either the old or new behaviour is desired. Datetime outputs should also respect the types used in the input data (i.e. cftime for iris and numpy.datetime64 for xarray when using standard calendars), but this can be changed to convert dates to numpy.datetime64 if possible by setting the parameter "preserve_iris_datetime_types=False" in feature detection and segmentation.

In general, extensive testing has been carried out to ensure that tobac works as expected given both Iris or xarray input. However, if you do encounter any issues in your own workflows, we would appreciate opening a github issue to highlight any problems.

Many thanks,

the tobac dev team

Changelog

Enhancements for Users

• MAJOR CHANGE: Feature detection and segmentation have been changed to use xarray DataArrays for representation of spatial fields instead of Iris Cubes. This change will allow for increased flexibility for input data and ease development. Support for Iris Cube input is maintained through a conversion wrapper. #354 & #417
• Some differences in the output of feature detection are present in the output from feature detection: when using xarray, the column names for coordinates will use the variable names, while with iris the columns will use the standard names. This differences reflects the different ways in which coordinates are named in xarray and iris, and can be overridden by the user using the use_standard_names parameter. #489

Bug fixes

• An issue with datetime output from feature detection being converted to cftime format erroneously was fixed, and datetime formats should now match the formatting in the input field. Time matching within a tolerance range now works with any combination of datetime formats #489

Documentation

• Example notebooks have been converted to use xarray, and have had minor enhancements to descriptions and visualisations. A notebook showing the legacy approach using Iris Cube input is retained #487

Internal Enhancements

• tobac.utils.internal.basic was restructured into coordinates and label_props utils, and new datetime and generators utils were added #489

All changes:

v1.5.5...v1.6.0

Full Changelog: https://github.com/tobac-project/tobac/blob/d277bc1c697f9e58fc9b2ef8aaf254837140e682/CHANGELOG.md