How to make the snapping distance/tolerance dynamic on the snapper and/or intersector

Hi @jdh​ ,

Thank you very much. That worked perfectly.

For anyone that hits a similiar situation, here is the PythonCaller code I used:

import fme
import fmeobjects
 
# Create a Snapper and call it using the value of the snapping_distance
# from the first feature receieved as the snapping tolerance. Used as the
# Snapper transformers does not normally allow the snappnig tolerance 
# to come from an attribute.
 
SNAPPER_FACTORY_TEMPLATE = """\
FACTORY_DEF {{*}} SnappingFactory                                      \
   FACTORY_NAME Snapper_2                                              \
   INPUT  FEATURE_TYPE Input                                           \
   SNAP_TYPE ALL                                                       \
   SNAP_TOLERANCE {snapping_tolerance}                                 \
   FLUSH_WHEN_GROUPS_CHANGE No                                         \
   OUTPUT_DEGENERATES_AS_COLLAPSED YES                                 \
   DO_NOT_STROKE_ARCS_FOR_VERTEX_SNAPPING                              \
   CLEANING_TOLERANCE AUTO                                             \
   OUTPUT SNAPPED FEATURE_TYPE Snapper_2_SNAPPED                       \
   OUTPUT UNTOUCHED FEATURE_TYPE Snapper_2_UNTOUCHED\
"""
 
class FeatureProcessor(object):
 
    def __init__(self):
        self.pipeline = None
        
    def input(self, feature):
        if self.pipeline is None:
            snappingDistance = float(feature.getAttribute("snapping_distance"))
            self.pipeline = fmeobjects.FMEFactoryPipeline("SnappingPipeline")
            snapperFactoryDefinition = SNAPPER_FACTORY_TEMPLATE.format(snapping_tolerance=snappingDistance)
            self.pipeline.addFactory(snapperFactoryDefinition)
        feature.setFeatureType("Input")
        self.pipeline.processFeature(feature)
        
    def close(self):
        if self.pipeline is not None:
            self.pipeline.allDone()
            resultFeature = self.pipeline.getOutputFeature()
            while resultFeature is not None:
                self.pyoutput(resultFeature)
                resultFeature = self.pipeline.getOutputFeature()

Then to use you just need to make sure the first feature to enter has a snapping_distance attribute set to the snapping tolerance you wish to use.

If you wish to change the config for the Snapper (eg use a snapping type other than Segment Snapping) just configure a Snapper how you want in a workspace, copy it and paste into a text editor. Then copy the resulting FACTORY_DEF into the SNAPPER_FACTORY_TEMPLATE variable above. If you wish to then customize any params based on attribute (as I have done with snapping_tolerance) above just update them in the String with the values you want.

Michael