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Question

Computing the percentage of the change of the data

  • April 22, 2019
  • 1 reply
  • 30 views

Hi FME Experts,

 

I have a feature class, and I received a new copy of this feature, I have used the "update detector" transformer to detects the changes between the two sets of input features.

for the updated data (geometry), I need to find a way to compute the percentage of the changing in the data.

I have tested the new release of the "ChangeDetector" transformer, but it does not give a percentage. of the change.

 

Please advise me about this matter.

 

Thank you in advance.

erik_jan
Contributor
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  • Contributor
  • April 22, 2019

Assuming your data is polygons and the ID does not change, this could be the workflow:

Calculate the area of the original polygon (AreaCalculator): area_orig

Use an AreaonAreaOverlayer (group by ID) and Tester (_overlaps > 1) to find the overlapping parts.

Use a Aggregator (group by ID) on the overlapping parts.

On the overlapping part, repeat the AreaCalculator to get area_new.

Your change will be: (area_orig - area_new) / area_orig

This can be calculated using the ExpressionEvaluator

Hope this helps.


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