Append/Insert geoprocessing results into an existing feature class (polyline midpoints)

Question

I plan to run a scheduled server job on a feature class in an Oracle 18c/10.7.1 geodatabase.

The job would:

1. Truncate the rows in an existing feature class
2. Generate new rows from a geoprocessing tool (FeatureVerticesToPoints / midpoints)
3. Insert/append the geoprocessing rows into the feature class

Note: I would like to do this without needing to temporarily store any sort of intermediate results in a temporary feature class/GDB.

---

I've gotten part-way there:

import arcpy
conn = "Database Connections\\DEV.sde\\"
input_lines = "OWNER.ROAD"
existing_fc = "OWNER.SCHED_ROAD_MIDPOINT"

arcpy.TruncateTable_management(conn + existing_fc)
arcpy.FeatureVerticesToPoints_management(conn + input_lines, conn + existing_fc, "MID")

#arcpy.Append_management(, , "TEST", "", "")

---

Question:

I'm not sure how to use FeatureVerticesToPoints_management as the input in the append process.

Is there a way to append/insert geoprocessing results into an existing feature class using ArcPy?

Answer 1

You can't* do this using FeatureVerticesToPoints without writing to an intermediate feature class.

You have two options:

1. Use FeatureVerticesToPoints and write to the in_memory workspace, then append:

   arcpy.management.FeatureVerticesToPoints(input_lines,  "in_memory\\output_points", "ALL")
   arcpy.management.Append("in_memory\\output_points", existing_fc, "TEST")
   

2. Use a SearchCursor to get the vertices, convert to points then an InsertCursor to populate the output:

   with arcpy.da.SearchCursor(input_lines, ['SHAPE@', '*']) as s_rows:
       with arcpy.da.InsertCursor(existing_fc, ['SHAPE@', '*']) as i_rows:
           for row in s_rows:
               line = row[0]
               for i in range(line.partCount):
                   points = line.getPart(i)
                   for point in points:
                       i_rows.insertRow([point] + list(row[1:]))
   

* You can of course overwrite existing_fc but that's not a useful option in most enterprise GDBs.

Answer 2

I've built on @user2856's answer:

1. Loop through a list that has 3 rows. Each row has an input FC, target FC, and an ID field.
2. For each row in the list:
   • Truncate the target FC
   • Populate the target FC with midpoints from the input FC (target FC fields are: SHAPE, MIDPOINT_X, and MIDPOINT_Y)
   • Populate the ID field in the target FC

---

Caution! The target FCs will get truncated! All records in the target FCs will be deleted.

import arcpy
conn = "Database Connections\\<YOUR CONNECTION.sde>\\"

#This script only works for polyline feature classes (not polygons or points).
#Caution! The target FCs will get truncated! All records in the target FCs will be deleted.

#       INPUT FC               TARGET FC                     ID FIELD (for both the input FC and the target FC)    
lstFC = [\
        ["<OWNER>.<SIDEWALK>", "<OWNER>.S_SIDEWLK_MIDPOINT", "SDW_ID"   ],\
        ["<OWNER>.<SEWER>"   , "<OWNER>.S_SEWER_MIDPOINT"  , "SEWER_ID" ],\
        ["<OWNER>.<ROAD>"    , "<OWNER>.S_ROAD_MIDPOINT"   , "ROAD_ID"  ],\
        ]

def ReloadMidpoints():
    for fc in lstFC:
        inputFC  = conn + (fc)[0]
        targetFC = conn + (fc)[1]
        idField  = (fc)[2]

        arcpy.TruncateTable_management(targetFC)
        print "<" + targetFC + "> has been truncated."

        with arcpy.da.SearchCursor(inputFC, ['SHAPE@', idField]) as s_rows:
            with arcpy.da.InsertCursor(targetFC, ['SHAPE@', idField, "MIDPOINT_X","MIDPOINT_Y"]) as i_rows:
                for row in s_rows:
                    Midpoint = row[0].positionAlongLine(0.50,True).firstPoint
                    rowVals = [(Midpoint.X,Midpoint.Y),s_rows[1],Midpoint.X,Midpoint.Y]
                    i_rows.insertRow(rowVals)

        print "<" + targetFC + "> has been reloaded with midpoints that were generated from <" + (inputFC) + ">."
        print ""

ReloadMidpoints()
print "Complete."