[QGIS-Developer] Processing 3.0: Possible change to the Convex Hull algorithm

Anita Graser anitagraser at gmx.at
Tue Jun 27 12:06:29 PDT 2017

On Tue, Jun 27, 2017 at 7:45 AM, Matthias Kuhn <matthias at opengis.ch> wrote:

> On 6/27/17 7:19 AM, Paolo Cavallini wrote:
> > Hi Nyall,
> >
> > Il 27/06/2017 01:41, Nyall Dawson ha scritto:
> >
> >>> This discussion relates to the "Convex Hull" algorithm. I'd like to:
> >>>
> >>> 1. Drop the "Field (optional, only used if creating convex hulls by
> >>> classes)" option and the accompanying method choice used to set the
> >>> convex hull to 'create convex hulls based on field'.
> >
> > I understand the rationale behind this; I'm just a bit worried it will
> > be more complicated and less understandable for users.
> > Perhaps adding another module that does both commands (collect + convex
> > hull) in one shot would be useful?
> > All the best.
> Maybe there is the need to ship some often-used models by default then?
> Thinking of code complexity and maintainability, it makes much sense to
> modularize algorithm code as much as possible

​I absolutely understand the reason from an engineering point. From the
user point - and as someone answering a lot of user questions - it is
predictable that end users will be confused.

Idea: Have a warning if a user tries to run the new "convex hull" on a
dataset with single part geometries?

Best wishes,
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