[GIS] Polygonizer Error “‘NoneType’ object has no attribute ‘isMultipart’ See log for more details”

errorqgisqgis-processing

I'm trying to polygonize. But I'm getting an error message:

'NoneType' object has no attribute 'isMultipart' See log for more
details

Basically what I'm trying to do is divide the city into blocks so I can assign a value to each block.

I'm not sure if I'm getting the error because of something about the lines or someting in the attribute table… Or something else.

Here's a closeup of what the street centerlines look like.

Maybe I need to clean up the lines or something, not sure. But anyway here's the error message I get when I run it.

Best Answer

From Python: Attribute Error - 'NoneType' object has no attribute 'something':

NoneType means that instead of an instance of whatever Class or Object you think you're working with, you've actually got None. That usually means that an assignment or function call up above failed or returned an unexpected result.

This means that there are probably some features (geometries) that are not valid. You may check your input layer using the Check validity algorithm available from the Processing Toolbox and then try again to run the Polygonize tool. It will allow you to repair any eventually invalid geometry.

If it still doesn't work, you may also try the Lines to polygon tool or the Convert lines to polygons SAGA tool, which are both available from the Processing Toolbox.

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[GIS] Polygons between contour lines in QGIS

isMultiPart() is a method of class QgsFeature. The error 'NoneType' object has no attribute 'isMultipart' means that at least one feature has geometry() of None. It might be a degenerated contour line with length 0, or some other error concerning geometry.

If you have problems using a provided tool, then first check geometry, eg delete polyline having length equal 0, polygon having area equal 0, or check their topology. This problems may or may not raise errors in tools, depending on which error handling the developer has taken into consideration.

In case you have written python code that raises this error, test the QgsGeometry object before using its methods or process the underlying geometry store:

geom = geometry()
if geom:
    if not geom.isEmpty():
        # do something useful

Or more in-depth checking:

geom = geometry()
if geom:
    err = geom.validateGeometry()
    if not err:
        # do something useful
    else:
        print '%d geometry errors detected' % len(err)

[GIS] QGIS 2.14.3 Processing Dissolve error “local variable ‘nElement’ referenced before assignment See log for more details”

You can use Vector polygon tools > Polygon dissolve (by attribute) from SAGA in the Processing Toolbox. I had the same issue.

Best Answer

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[GIS] Polygons between contour lines in QGIS

[GIS] QGIS 2.14.3 Processing Dissolve error “local variable ‘nElement’ referenced before assignment See log for more details”

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