Update cursor and SHAPE@XY token problem

[PanagiotisChiotis]

Hello everyone,

I am new to Python and ArcPy.

I am testing the script below which is running for a point feaure class, but not for a line feature class.

1. import arcpy
2. arcpy.env.workspace = r"D:\Student\PYTH\6_Geometry_objects\SanDiego.gdb"
4. # Variables
5. featClass = "MajorAttractions2"
6. fields = ["SHAPE@XY"]
7. exp = "OBJECTID = 4"
9. pnt = arcpy.Point()
10. pnt.X = 306400
11. pnt.Y = 4098400
13. with arcpy.da.UpdateCursor(featClass, fields, exp) as cur:
14.     for row in cur:
15.         row[0] = pnt
16.         cur.updateRow(row)
18. print "Script completed"

In the latter case, I am getting the following error message: "exceptions.SystemError: error return without exception set" for line 16.

Thank you in advance,

Panagiotis

[DarrenWiens2]

Ignoring the fact that you are trying to create a line from a single point (which surprisingly works), does the line feature class contain a feature at OBJECTID = 4?

[PanagiotisChiotis]

Hello Darren,

I am not trying to create a line feature class, but rather shift a feature of it. Both point and line feature classes already exist. And, yes, "OBJECTID = 4" is a valid expression in both cases.

Regards,

Panagiotis

[OwenEarley]

SHAPE@XY for a line feature will return the feature centroid. You will need to use SHAPE@ and then locate the vertex point on the polyline to update.

These pages have more detail:

• Reading geometries - ArcGIS Help (10.2, 10.2.1, and 10.2.2)
• Writing geometries - ArcGIS Help (10.2, 10.2.1, and 10.2.2)

[DarrenWiens2]

I thought you had to do it vertex by vertex, too, but this post seems to disagree: https://arcpy.wordpress.com/2012/11/15/shifting-features/

It shifts geometry all as one.

[OwenEarley]

Good catch - I hadn't seen that post.

[JoshuaBixby]

You didn't catch it because documenting important functionality like that on a third-party blogging platform is, well, poor taste.  It would be nice and a bit more enterprise-y if the ArcGIS Python development team did more blogging within an Esri domain, say GeoNet maybe.

[DanPatterson_Retired]

1. exp = "OBJECTID = 4"  are you sure it is a valid where clause, it looks like an assignment statement, did you try
2. exp = "OBJECTID == 4"

[DarrenWiens2]

1. Should be correct through SQL goggles.

[DanPatterson_Retired]

​sigh.... python googles always on