[QGIS-Developer] FME to QGIS functionality mapping

[Nyall Dawson]

Hi list,

Just wanted to give a heads up on a document I've recently completed,
which maps existing FME functionality across to the equivalent QGIS
Processing or Expression equivalent:

https://github.com/nyalldawson/qgis-processing-hitlist/blob/master/fme.md

Since FME transformers are both algorithm-like and expression-like
functionality, the document splits the QGIS equivalents into columns
for both algorithms and expressions. Wherever the transformer
functionality doesn't apply, a "N/A" is entered in the corresponding
column (e.g. the "StringCaseChanger" transformer doesn't make sense
the implement as a QGIS Processing algorithm -- it's equivalent is
instead the expression functions "lower", "upper" and "title". And
conversely the "DuplicateFilter" transformer maps to the Processing
algorithms "Delete Duplicate Geometries" and "Delete duplicates by
attribute", but doesn't make sense to have an expression function
equivalent!)

There's also Transformers in FME which really don't need an equivalent
in QGIS -- e.g. those relating to styling features.

Overall we have a good level of coverage of the most important
functionality. There's a LOT of low-hanging fruit which could easily
be addressed in small PRs (e.g. things like the
"CharacterCodeExtractor" transformer would be a trivial task to
implement as a new QGIS expression function ... a GREAT task for
someone getting started with QGIS development!).

(and just for completeness - QGIS offers hundreds of processing
algorithms and expression functionality which **doesn't** have
equivalents in FME. I suspect the reverse document would have just as
many "missing" cells!)

Feedback welcome! At some stage I think it would be nice to move this
document across to the QGIS repo, and possibly pull into the QGIS
documentation itself (along with similar documents for Arc/...
functionality!)

Nyall