topic Is it possible to move a vertex in a polyline with arcpy? in Python Questions

Is it possible to move a vertex in a polyline with arcpy?

Marianne_BilstedWiese — Wed, 02 Oct 2013 15:21:13 GMT

Hi

For a featureclass of polylines with 2 vertices each, I want to be able to keep the line itself, startpoint and the angle, but move endpoint to a specific length.

I am doing this in a versioned geodatabase, and currently I can put a new line into the geometry, but the problem is, there are featurelinked annotations which are reset, when the whole line is changed.

I wonder whether it is possible, since I already am in edit mode, to just move lastpoint of the existing line?

Perhaps this is not possible with arcpy?

Best Regards
Marianne Wiese

import arcpy, time, traceback
arcpy.env.workspace = 'Database Connections/mbw.sde'
inFeatures = 'G100.geopoint_mbw_20130930/G100.geopoint_line_2'
newLength = 550
n = 0
try: 
 uCursor = arcpy.da.UpdateCursor(inFeatures, [ 'OID@', 'SHAPE@'])
 edit = arcpy.da.Editor(arcpy.env.workspace)
 edit.startEditing()
 edit.startOperation()
 for row in uCursor:
  line = row[1]
  factor = newLength/line.length
  X2 = line.firstPoint.X + factor * (line.lastPoint.X - line.firstPoint.X)
  Y2 = line.firstPoint.Y + factor * (line.lastPoint.Y - line.firstPoint.Y)
  array = arcpy.Array([line.firstPoint, arcpy.Point(X2,Y2)])
  newLine = arcpy.Polyline(array)
  row[1] = newLine
  uCursor.updateRow(row)
  n += 1
  if (n % 1000 == 0):
   print time.strftime('%H:%M:%S'), ':   ', n
except:
 tb = traceback.format_exc()
 print tb
finally:
 del uCursor
 edit.stopOperation()
 edit.stopEditing(True)
 del edit
print 'all done'

Re: Is it possible to move a vertex in a polyline with arcpy?

SchoppMatthieu — Wed, 02 Oct 2013 21:46:30 GMT

Is changing the last point X coordinate value according the coordinate system distance unit working ?

Re: Is it possible to move a vertex in a polyline with arcpy?

Marianne_BilstedWiese — Thu, 03 Oct 2013 09:02:10 GMT

Thanks for answering, Matshopp.

However, as you can see in my code, I already read the vertex positions from the geometry. Problem is, that Arcpy's access to polyline object properties is readonly, so that I must make a new line and put that into geometry object.

I guess it has to do with the granularity of arcpy's methods.

I had hoped for another library to exist, which could programmatically go into edit mode more in details.

Best regards
Marianne