Bug report #15822

Singleparts to multi-part polygon algorithm uses NULL values also

Added by Sharachchandra Lele almost 4 years ago. Updated over 3 years ago.

Status:Closed
Priority:Normal
Assignee:-
Category:Processing/QGIS
Affected QGIS version:2.14.2 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 #:23742

Description

I have a polygon shapefile with an attribute villageID, in which some polygons have the same attribute value and so they should together form a single multi-part polygon. Some other polygons have NULL in this villageID field. When I run the tool Vector>Geometry Tools>Singleparts to Multipart (from the menu or from Procsesing Toolbox, and whether I use the GDAL version or the QGIS geoalgorithm version), the resulting shapefile does merge the repeated villageIDs into multi-part polygons. But it ALSO merges ALL the polygons that had this field = NULL into a SINGLE multi-part polygon. In effect, it is treating all NULL values as equal, when in fact it should treat NULL as 'not known' and ignore those polygons. If I run a 'find duplicates' query in MS-ACCESS on the attribute table dbf, the query ignores those rows where villageID=NULL, which IMHO is the correct method.

Associated revisions

Revision a944f7c4
Added by Alexander Bruy over 3 years ago

[processing] handle NULL values in the Singleparts to multiparts (fix #15822)

Revision 7ee1cbfa
Added by Alexander Bruy over 3 years ago

Revert "[processing] handle NULL values in the Singleparts to multiparts (fix #15822)"

This reverts commit a944f7c4c1010767abb811200686e327040c2d32.

Revision e4d745fe
Added by Alexander Bruy over 3 years ago

[processing] handle NULL values in the single to multi algorithm (fix #15822)

Revision b56e46da
Added by Alexander Bruy over 3 years ago

[processing] handle NULL values in the single to multi algorithm (fix #15822)

Revision 4dab1f85
Added by Alexander Bruy over 3 years ago

Merge pull request #4560 from alexbruy/processing-singletomulti

[processing] handle NULL values in the single to multi algorithm (fix #15822)

Revision e3d79a1f
Added by Alexander Bruy over 3 years ago

Merge pull request #4562 from alexbruy/processing-singletomulti-3

[processing] handle NULL values in the single to multi algorithm (fix #15822)

Revision fe7c981a
Added by Alexander Bruy over 3 years ago

[processing] handle NULL values in the single to multi algorithm (fix #15822)

Revision 49a7158a
Added by Alexander Bruy over 3 years ago

Merge pull request #4565 from alexbruy/processing-single2multi

[processing] handle NULL values in the single to multi algorithm (fix #15822)

History

#1 Updated by Alexander Bruy over 3 years ago

  • Category set to Processing/QGIS

#2 Updated by Alexander Bruy over 3 years ago

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

Fixed in a944f7c4c1

#3 Updated by Jürgen Fischer over 3 years ago

  • Status changed from Closed to Reopened
  • Regression? set to No
  • Resolution deleted (fixed/implemented)
  • Easy fix? set to No

#4 Updated by Alexander Bruy over 3 years ago

  • Status changed from Reopened to Closed
  • % Done changed from 0 to 100

#5 Updated by Giovanni Manghi over 3 years ago

  • Resolution set to fixed/implemented

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