Bug report #19593

"Classify" button in graduated symbology may make too small a range

Added by Ryan Desmond almost 6 years ago.

Affected QGIS version:3.2.1 Regression?:No
Operating System:Ubuntu 16.04.5 Easy fix?:Yes
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:27420


Auto-classified ranges that are created on the graduated symbology preference panel may not include features at the extremes of the field used for the ranges.


  1. Load the attached [[attachment:file.zip]] into QGIS
  2. Open the layer properties / symbology
    1. Select "Graduated"
    2. Select "val" as the column
    3. Select "Classify" to generate 5 classes from the data
  3. Hit "Okay" to return to the main view

Qgis symologies properties screenshot


When looking at the correct location on the map, all 6 points are visible. Points are located at (0,0) (10,0) (20,0) (30,0) (40,0) (50,0).


When looking at the correct location on the map, only 4 points are visible. The points with the lowest and highest values are outside of the generated categories and are not displayed. See the attached image (which has a duplicate of the initial layer to show text where the points should be.)

Qgis main display screenshot

points.geojson - Example geojson file (914 Bytes) Ryan Desmond, 2018-08-10 07:15 PM

points_displayed_in_qgis.png - Qgis main display screenshot (75 KB) Ryan Desmond, 2018-08-10 07:19 PM

symbology_properties.png - Qgis symologies properties screenshot (126 KB) Ryan Desmond, 2018-08-10 07:19 PM

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