What is the python expression for the second, third, fourth etc etc vertex along a line feature?

Question

What is the python expression for the second, third, fourth etc etc vertex along a line feature? !shape.firstpoint¡ is the first vertex and !shape.lastpoint¡ is the last vertex, but what's the expression for other vertices down the line?

JoshuaBixby · Answer

I agree with Luke that cursors are best when working with more in-depth properties or methods of geometries.  If you must work with the Field Calculator, the "Code samples -- geometry" section of Calculate Field examples—Help | ArcGIS Desktop shows how you would retrieve the geometry and then process it in a code block.

LukeWebb · Answer

Theres no specific way to do this, this is likely a design decision, as features can have theoretically unlimited vertexes so loading all this info to populate a dictionary etc, could be expensive and have potential to massively slow down cursors. Check out this article, that tells you the exact same thing I could but using many more words and much more coherently: Reading geometries—ArcPy Get Started | ArcGIS Desktop The code at the bottom should allow you to do as you require. import arcpy infc = arcpy.GetParameterAsText(0) # Enter for loop for each feature # for row in arcpy.da.SearchCursor(infc, ["OID@", "SHAPE@"]): # Print the current multipoint's ID # print("Feature {}:".format(row[0])) partnum = 0 # Step through each part of the feature # for part in row[1]: # Print the part number # print("Part {}:".format(partnum)) # Step through each vertex in the feature # for pnt in part: if pnt: # Print x,y coordinates of current point # print("{}, {}".format(pnt.X, pnt.Y)) else: # If pnt is None, this represents an interior ring # print("Interior Ring:") partnum += 1p ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍