Bug report #13105
Rounding error in extreme classes when converting graduated to rule-based rendering
| Status: | Closed | ||
|---|---|---|---|
| Priority: | Normal | ||
| Assignee: | - | ||
| Category: | Symbology | ||
| Affected QGIS version: | 2.10.0 | Regression?: | No |
| Operating System: | Easy fix?: | No | |
| Pull Request or Patch supplied: | No | Resolution: | end of life |
| Crashes QGIS or corrupts data: | No | Copied to github as #: | 21170 |
Description
I stumble onto a small bug that can lead to geographic entities falling out of class bounds when converting from graduated renderer to rule-based renderer. The consequence is a visual absence on the canvas for those entities.
This seem to occur only when the mapped field have a higher number of decimal places than what the script which generate converted rules decide to store (my field have 15 places, the generated rule have only 6)
I joined an example file an here are the steps to reproduce:- Load the shapefile (UTF8)
- Set up a graduated style and do a classification on the field "idx_vielli"
- Apply to check that all entities are correctly rendered in canvas
- Go back to style and set it to rule-based, the classification is translated into rules
- Apply and notice that entities with minimum and maximum value disappear from the canvas
- Edit the generated rules and round boundary as following:
Remove 1 to the last digit of the lower bound of the lowest class
Add 1 to the last digit of the upper bound of the highest class
- Notice that all entities now show up correctly
Proposed fixes
Option 1
Modify the script which convert graduated class into rules so that it apply a failsafe rounding on the lowest and highest class. This should be quick if one know where to look for.
Option 2
Ensure that the conversion script never round boundary when converting from graduated class.
While better in theory this should be considered carefully as it could generate unknown side effects.
I tested this in a 2.6 QGis version and the bug is also present so bug-fixes should also be applied to LTR cause it seem pretty old.
Thank you in advance for taking this into consideration!
Martin
History
#1
Updated by Giovanni Manghi over 9 years ago
- Category set to Symbology
#2
Updated by Giovanni Manghi over 7 years ago
- Easy fix? set to No
- Regression? set to No
#3
Updated by Giovanni Manghi over 5 years ago
- Resolution set to end of life
- Status changed from Open to Closed
End of life notice: QGIS 2.18 LTR
Source:
http://blog.qgis.org/2019/03/09/end-of-life-notice-qgis-2-18-ltr/
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