[Qgis-developer] Teaching Processing: notes from the wild

[Alexander Bruy]

Hi,

2013/10/18 Paolo Cavallini <cavallini at faunalia.it>:
> * Random selection: the selection does not appear, as the module is not refreshing
> the view
Seems fixed in master. Also similar bug was closed about 5 days ago, see
https://hub.qgis.org/issues/8127#change-45578

> * Split randomly: the % is not exact (e.g. if I select a 20/80 split, I get 22/78 etc.)
I can see only SAGA algorithm with this name. Not sure, but seems this is
upstream (SAGA) bug.

> * Create graticule from extent: with lines, one of the points (first North-West) is
> left out; with polygons it is ok
Seems same as previous.

> * In the Log viewer, the button Cancel is misleading, and can lead to loss of
> important data a bit too easily; better to give a warning before actually deleting
I suppose you mean Clear button, right? Added in master just now.

> * the Field calculator is barely usable without a dropdown list of fields and
> functions; on win it does not seem to work (most or all calculations end up with all
> NULLs); unclear if this is due to minor edit issues from users (quite likely without
> the dropdowns)
Maybe I'm wrong, but currently there is no way to create such widgets
and use them
in Processing algorithms.

> * it seems impossible to make conditional models (if this value is ... then run this
> command, else this other one): am I correct? this would be a major improvement IMHO
Yes, there are no support for conditional expressions and loops in modeler.
I don't remember exactly, but this is a complex issue and adding such feature
will require a lot of work.

--
Alexander Bruy