Transferring XY coordinates of point from one feature class to point in second feature class using ArcPy

Question

I have a small list of points, testingPoints, that need their geometry (x and y points) transferred to points within a larger dataset, baseCentroids. The datasets share a common field POINTID to help identify one for the other. This is the code I have:

rowFields = ['POINTID','SHAPE@X', 'SHAPE@Y']
rows = arcpy.SearchCursor(testingPoints, rowFields)
for row in rows:
    whereClause1 = "POINTID = '" + row.getValue('POINTID') +"'"
    pointFields = ['POINTID','SHAPE@X', 'SHAPE@Y']
    points = arcpy.UpdateCursor(baseCentroids, whereClause1, pointFields)
    for point in points:
        point.setValue("SHAPE@X", row.getValue(SHAPE@X))
        point.setValue("SHAPE@Y", row.getValue(SHAPE@Y))

        #tried this method as well
        #point[1]=row[1]
        #point[2]=row[2]

        rows.updateRow(row)

While to me this looks correct it is not.

Answer 1

Using the three basic principles of ArcPy cursors

1. Always use Data Access cursors
2. Avoid nesting cursors (instead, search once into a dictionary, then use that for lookup)
3. Use Geometry where possible

and assuming

• The "small list" of point IDs is a small subset of the overall point set, and
• The coordinate reference systems of the two feature classes are identical,

we get:

fieldNames = ['POINTID','Shape@']
pointById = {}
with arcpy.da.SearchCursor(testingPoints,fieldNames) as cursor:
    for row in cursor:
        pointById[row[0]] = row[1]

with arcpy.da.UpdateCursor(baseCentroids,fieldNames,
            "{:s} IN ('{:s}')".format('"POINTID"',"','".join(list(pointById)))) as cursor:
    for i,row in enumerate(cursor):
        row[1] = pointById[row[0]]
        cursor.updateRow(row)
print("{:d} feature{:s} updated".format(
        i,'' if i == 1 else 's'))

Further insights:

• Never mix DA and non-DA cursor syntax
• The field_names parameter always comes before where_clause
• Never attempt to update SearchCursor rows
• Never perform string math (use str.format() instead)
• Leverage str.join() to construct lists (but keep track of the quotes)

Note: While this does look like it's correct, you should test it (and add print statements anywhere you're unsure of what is happening)