Bug report #20840

Keep N biggest parts documentation is incorrect

Added by Odysseas Vl about 1 year ago. Updated about 1 year ago.

Status:Closed
Priority:Normal
Assignee:-
Category:Documentation and Help
Affected QGIS version:3.4.2 Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:fixed/implemented
Crashes QGIS or corrupts data:No Copied to github as #:28659

Description

QGIS 3.4.2 , Windows 10, 64bit

Keep N biggest parts does not consider the input "Parts to keep" returning all the features from the shapefile input and not the number specified, e.g. 1.
Hard disc saving or temp file does not change outcome.

Example that returns all the features without selecting the 3 biggest:
_Processing algorithm…
Algorithm 'Keep N biggest parts' starting…
Input parameters: { 'OUTPUT' : 'C:/.../test.shp', 'PARTS' : 3, 'POLYGONS' : 'C:/.../in.shp' }

Execution completed in 0.47 seconds
Results: {'OUTPUT': 'C:/.../out.shp'}

Loading resulting layers
Algorithm 'Keep N biggest parts' finished_

and from processing command history:

processing.run("qgis:keepnbiggestparts", {'POLYGONS':'C:/.../in.shp','PARTS':3,'OUTPUT':'C:/.../out.shp'})

History

#1 Updated by Nyall Dawson about 1 year ago

  • Status changed from Open to Feedback

You're misinterpreting what this algorithm does - it keeps all features from the input layer, removing parts from individual geometries (e.g. multipolygons) until those geometries have the specified max number of parts.

#2 Updated by Odysseas Vl about 1 year ago

Maybe I am misinterpreting indeed, I was following the documentation explanation from here: https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html#id261
If the case is as Nyall says, then for me the doc was confusing

#3 Updated by Nyall Dawson about 1 year ago

  • Category changed from Vectors to Documentation and Help
  • Status changed from Feedback to Open
  • Subject changed from Keep N biggest parts does not work as expected to Keep N biggest parts documentation is incorrect

#5 Updated by Harrissou Santanna about 1 year ago

  • Status changed from Open to Closed
  • Resolution set to fixed/implemented

Description is fixed in docs (would be online in a day)

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