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I used yesterday, in QGIS 3.2.3 the tool to convert multiline to a single line ("multipart to single part").

I chose the option of the command "multipart to single part" the geometry feature (line) and marked z dimensions. QGIS save right the temporary layer in format shape, a shapefile with z dimension included.

When I tried to eliminate z dimension with ogr2ogr and inserted in QGIS, the program consider that the layer is a single line geometry. Who can help me?

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  • Single (as not multi) or simple (as not having Z values)? Also, can you provide the ogr2ogr command you are using.
    – Alexandre Neto
    Commented Oct 20, 2018 at 8:08
  • I have a layer (.shp) with multiline (i see that on layer's proprieties). I did the command multipart to singlepart to change layer's proprieties from multiline to singleline. QGIS in this way view a new temporary layer with singlepart, this is so good! When i tried to export that temporarely layer i saw on proprieties that this shape had multiline not single line. The question is how to keep geometry singleline when create a new shapefile from a temporary layer that have single line. Better?
    – Fabolous
    Commented Oct 23, 2018 at 10:24
  • I have a right new shapefile (not temporary) with singleline geometry when i insert z within the "multipart single part" command. I don't want a shapefile with singleline and z, but only single line. But if i drop z and then export temporary layer, the new shapefile have multiline string not single!
    – Fabolous
    Commented Oct 23, 2018 at 10:27
  • I used ogr2ogr but not work, QGIS show that new layer have multiline string not single!
    – Fabolous
    Commented Oct 23, 2018 at 10:34

2 Answers 2

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In QGIS, the purpose of the Multipart to singlepart tool is not to change the layer's geometry type, but instead to separate features containing several (geometry) parts into individual features.

If you want to change the layer geometry type, you can the Convert Geometry Type instead. In the New geometry type option select Linestrings.

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  • I used Convert Geometry Type and the output is right (single line), but the layer is temporary (virtual). It's isn't a shapefile saved on disk. For this reason i tried to export temporary layer as a new shapefile with right geometry (single line e not "Line (MultiLineString)", but not work.
    – Fabolous
    Commented Oct 23, 2018 at 12:24
  • Instead of using a temporary layer as output, select the path to your disk in the format you need.
    – Alexandre Neto
    Commented Oct 23, 2018 at 12:33
  • I clicked on command Convert Geometry Type, i chosed the input layer that i need and i selected into "new geometry type" the geometry "linestrings". I clicked on button located near "Create temporary layer", then i did "Save to file" and saved it into D:\, the new layer has "Line (MultiLineString)". It is not right, i would Line (LineString)
    – Fabolous
    Commented Oct 23, 2018 at 13:01
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    You are right Sir, I just tried it with some local data. There is something wrong with the export function.
    – Alexandre Neto
    Commented Oct 23, 2018 at 13:16
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    Better create a ticket on the bug tracker: issues.qgis.org/projects/qgis/issues
    – Alexandre Neto
    Commented Oct 23, 2018 at 13:19
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Three days ago they are answered to my QGIS ticket. They said that from QGIS 3.0 the program load always multi part geometry. The only way to work with single part geometry, is work with new format geopackage.

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  • Old comment but even as of 2023 this is still an issue, thanks to your comment I found out that Convert geometry type > Save as geopackage is the only thing that works. Although it's only an issue because of a deprecated/abandoned plugin that only works with LineString geometry type...
    – she_weeds
    Commented Dec 21, 2023 at 10:41

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