Hi Nyall, On 04/03/19 12:11, Nyall Dawson wrote: > Hi list, > > Just raising the discussion about what we should do with SAGA > Processing algorithms when the results generated by SAGA are known to > be incorrect (i.e. there's a bug in SAGA itself). > > Specifically, the SAGA difference and symmetric difference algorithms > generate incorrect results. See https://issues.qgis.org/issues/21354, > and the results from > https://github.com/qgis/QGIS/blob/master/python/plugins/processing/tests/testdata/saga_algorithm_tests.yaml#L318 > . This seems to be a general problem with the algorithms, not isolated > to particular input data. > > My gut feeling is: we should "deprecate" these algorithms (which means > they continue to work for existing models, but are hidden from the UI > and cannot be run from the toolbox or added to new models). I don't > see the value in exposing broken algorithms when we have robust > alternatives (the native QGIS difference/symmetric difference > algorithms are very fast, stable, and well tested), and potentially a > lot of harm. > > Thoughts?
thanks for raising this. I fully agree, and will push things a bit further: IMHO we should hide all algs from other backends when we have a robust alternative. This means qgis core alg should: * cover the full range of options available in the alternative command (often e.g. GRASS has a number of options that can be useful in special cases) * be robust even for huge data sets (e.g. GRASS is usually conservative in the use of memory, and can complete analyses even when other algs fail) * life is not perfect, so I think a power user should have the possibility of using other algs, in case we overlooked a special option, on temporarily if our alg is broken. I therefore suggest to: 1. have a list of the potentially duplicated algs 2. find one or more volunteers checking thoroughly the above 3. hiding those who correspond to the criteria 4. design a last resort way of using hidden algs. I'm available for 2. All the best. -- Paolo Cavallini - www.faunalia.eu QGIS.ORG Chair: http://planet.qgis.org/planet/user/28/tag/qgis%20board/ _______________________________________________ QGIS-Developer mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
