0

I routinely have to do the following workflow:

  • Map GPS points;-

  • Create lines based on those GPS points;

  • Split the lines at a set interval distance (every 50m, every 100m etc.)

  • Add from / to fields for chainages along the line.

I use ModelBuilder to automate this process as much as possible, but to generate the chainages, I need to use Excel because I have very limited experience with Python. So I generate the chainage values in Excel, then in the editor context in ArcGIS copy those values from Excel into the attribute table of my polyline features.

How can I transfer the logic I have in my Excel sheet over to Python to use in the Calculate Field tool within ModelBuilder?

The format of the from / to fields ends up being "K+MMM" where the K is the kilometer and the M's represent meters. So if I've got a starting point of 0km and 0m and an interval of 100m, the first chainage would read "0+000", followed by "0+100", "0+200".

Here are some screenshots of the logic in the Excel file: https://imgur.com/a/LHYyi0u

0

I found a snippet of code somewhere previously that does a lot of the work you are looking for. Here is a first cut at solving your problem. I have not looked at creating the GPS points or the lines. I assume you are starting with the lines completed.

import arcpy

arcpy.env.overwriteOutput = True
spatial_reference = arcpy.Describe(dids).spatialReference

# Create points along roads
loc = 't:/right_here'
lines = loc + '/lines.shp'
distance = 50 # meters
spatial_reference = arcpy.Describe(lines).spatialReference

mem_point = loc + '/points.shp'
arcpy.CreateFeatureclass_management(loc, points, "POINT", "", "DISABLED", "DISABLED", spatial_reference)
arcpy.AddField_management(mem_point, "LINE_ID", "INTEGER")
arcpy.AddField_management(mem_point, "FROM", "INTEGER")
arcpy.AddField_management(mem_point, "TO", "INTEGER")
search_fields = ["SHAPE@", "OID@"]
insert_fields = ["SHAPE@", "LINE_ID", "FROM", "TO"]
with arcpy.da.SearchCursor(lines, search_fields) as search:
    with arcpy.da.InsertCursor(mem_point, insert_fields) as insert:
        last_pt = -1
        for row in search:
            cur_point = 0
            try:
                line_geom = row[0]
                length = float(line_geom.length)
                count = 0
                oid = str(row[1])
                while count <= length:
                    point = line_geom.positionAlongLine(count, False)
                    insert.insertRow((point, oid, last_pt, cur_pt))
                    last_pt += 1
                    cur_point += 1
                    count += distance

            except Exception as e:
                print str(e.message)
  • Awesome thanks, I'll check this out as a starter! – stanleykubrick Oct 10 at 12:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.