Global Mapper v25.0

<Index in layer>

darrepac
darrepac Global Mapper User

Hello


I am opening a shapefile and I see in the attribute editor a <index in layer> value.

What it is?

I don't see such "index in layer" in QGIS, neither I do in the dbf file, I would like to understand what it represent


thx

Answers

  • bmg_mike
    bmg_mike Global Mapper Guru Moderator, Trusted User

    Those attributes with names enclosed in <> aren't actual attributes in the file, they are other attribute-like information that you can retrieve.

    The <Index in Layer> value is not an attribute in the data, it is an implicit attribute. It just means where the feature is in the file. The first feature has an index of 1, the second 2, etc.

    It's rare that you would need to make use of this information, but it's there if you need it.

  • darrepac
    darrepac Global Mapper User

    So How do I have to understand that my polylines is separated in 4 parts (4 different index in layer):


  • bmg_mike
    bmg_mike Global Mapper Guru Moderator, Trusted User

    Likely the Shapefile had a multi-part polyline. Each part of the polyline becomes a separate line feature in Global Mapper, so they have a separate index.

    For area features, Global Mapper has the concept of grouping, so a multi-part polygon will have a separate index for each part, but they will also be assigned a group number. There isn't currently a similar concept for line features in Global Mapper, but one could be added. I guess no one has asked for that for line features until now.

  • bmg_mike
    bmg_mike Global Mapper Guru Moderator, Trusted User

    Note that most formats don't have any concept of grouping multiple separate geometries as one multi-part feature. Shapefile is by far the most common format that has a concept like that.