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Problem: Changing the number of 'Class breaks' on the Symbology tab of the Layer Properties dialog box causes lost classification

Description

In some situations, when working with the Graduated color or Graduated symbols symbology methods, when the number of breaks is changed on the Symbology tab of the Layer Properties dialog box, all the class breaks are lost. This only happens if the number of features in the data exceeds the maximum sample size.

Cause

If there are existing Graduated colors or Graduated symbols on a large number of features (larger than the current sample size) and the Symbology dialog box is reopened and the number of classes is changed, the classification is lost. This is because a rescan of the data is not triggered.

Solution or Workaround

  • To avoid this problem, change the number of 'classes' from the 'Classification' dialog box.
    To change the number of classes:

    1. Click 'Classify' to open the 'Classification' dialog box.
    2. Change the number of classes in the 'Classes' drop-down list.

    [O-Image] Changing number of classes from Classification dialog box
  • To recover from the problem, reselect the value field on the 'Symbology' tab of the 'Layer Properties' dialog box. This causes a rescan of the data, and the number of classes can be changed successfully from the 'Symbology' tab of the 'Layer Properties' dialog box.