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Create group ID based on conditions?

  • April 3, 2025
  • 6 replies
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aron
Enthusiast
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The two lines below share the same end nodes and I want to give them a common group id for later processing. This is to be the step after a TopologyBuilder.

I thought this would be pretty simple, but have run aground. So how do I achieve this?

The geometris are to be left unchanged. I just want them to have a common “id” if they intersect at both ends.

The conditions for the ‘join’ are:

_from_node = _from_node AND _to_node = _to_node

OR

_from_node = _to_node AND _to_node = _from_node

Because sometimes the lines orient in different directions.

 

 

Best answer by takashi

Hi ​@aron ,

My idea is to create group ID by concatenating “_from_node” and “_to_node” with ascending order. The concept is shown below.

  • _node1 = If _from_node < _to_node then _from_node, Else _to_node
  • _node2 = If _from_node < _to_node then _to_node, Else _from_node
  • _group_id = @Value(_node1)_@Value(_node2) 
    danilo_fme
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    6 replies

    takashi
    Celebrity
    • takashiCelebrity
    • Best Answer
    • April 4, 2025

    Hi ​@aron ,

    My idea is to create group ID by concatenating “_from_node” and “_to_node” with ascending order. The concept is shown below.

    • _node1 = If _from_node < _to_node then _from_node, Else _to_node
    • _node2 = If _from_node < _to_node then _to_node, Else _from_node
    • _group_id = @Value(_node1)_@Value(_node2) 
    Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
    geomancer
    geomancer
    Evangelist
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    • geomancerEvangelist
    • Evangelist
    • April 4, 2025

    My idea is to create group ID by concatenating “_from_node” and “_to_node” with ascending order. 

    A very simple and elegant solution!

    If you want to, you can skip creating _node1 and _node2 by using _group_id =  @min(@Value(_from_node),@Value(_to_node))_@max(@Value(_from_node),@Value(_to_node))

     

    takashi
    ebygomm
    Influencer
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    • ebygommInfluencer
    • Influencer
    • April 4, 2025

    Would the NetworkTopologyCalculator not do this for you? 

    aron
    Enthusiast
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    • aronEnthusiast
    • Author
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    • April 4, 2025

    Would the NetworkTopologyCalculator not do this for you? 

    I believe that it would not get me where I want. There might be some trick with the NetworkTopologyCalculator that I dont know of, but when I have used it previously it gave me a ID for all the connected lines. I want to group only those that share the same start and end.

    ebygomm
    Influencer
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    • ebygommInfluencer
    • Influencer
    • April 4, 2025

    Ah too early in the morning for me, you’re actually looking for rings?

    aron
    Enthusiast
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    • aronEnthusiast
    • Author
    • Enthusiast
    • April 4, 2025

    Ah too early in the morning for me, you’re actually looking for rings?

    I haven't thought about it that way, but two part rings would be an accurate description. AreaBuilder does not work for my use case though, it gives far to many false positives. 

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