PARCEL UPDATER

the nationwide parcel service needs to be updated and the data needed for the update is provided via ftps from the provider. the bulk of the work is to get all the counties provided (over 3,000) compiled to the state level, and this script accomplishes that task. the below details provide information about each component of the script and also instructions for how to update this dataset.

main.py

the file where input paramaters are changed, name of the output_workspace and where the unzipped data_dir (path) exists. to run this programmatic upate process for the parcels, edit and run this main.py file using the esri provided idle, or another method if you prefer, making sure you have access to the arcpy package.

iterator.py

the main part of this workflow which iterates through each county folder and geodatabase provided in data_dir, makes a copy of the parcel polygon featureclass if it exists, runs repair geometry on the copied polygon, builds a pre-process count dictionary (count_dict), and builds the process dictionary (process_dict) used for processing in compiler.build. once process_dict is compiled, there are some print statements showing counts of gdbs and featureclasses, the dictionaries are written to file for reference, and the compiler.build function is called using process_dict as instructions.

data directory structure before processing:

• YYYYMMDD (parent folder with date of update containing all data)
  • DMP_DELIVERY_YYYYMMDD.xlsx (provided metadata; provided county of parcel polygons and unmatched property points)
  • ZIPS (child folder containing all state county parcels in zip file; will need to extract all to current directory before running script)
    • ST_COUNTY (over 3,000 folders; format is state abbreviation, ST + underscore + county name COUNTY)
      • ST_COUNTY.gdb (geodatabase for the county)
        • Parcels_w_Attributes_ST_COUNTY (actual polygon parcel featureclass; the only featureclass we care about)
        • Unmatched_Propertypoints_ST_COUNTY (unmatched parcel locations; we don't use this)

compiler.py

after much testing, this function is now a simple loop to iterate through the process_dict keys, which are state names. it runs arcpy.management.Merge() on the values for each key which is a list of county parcel featureclasses with the full path (you can reference this input dictionary in the output text file from iterator.py). once a state has merged, the output polygon featureclass will be in the output_workspace.

counter.py

the counter.py has two functions within the file. the post_work function runs a count for each state featureclass after they have been compiled in the output_workspace and appends that number to the count_dict for the appropriate state key in the 1 index position. the counter.py file also contains the write_dict function which writes the dictionaries to file. when the the post_work function runs to get the post count for count_dict, it will add a second number to the list for each state key, the first ([0] index) will be the pre process count and the second ([1] index) will be the post process count.

• the pre and post counts are meant to be a simple comparison of pre and post processing results to see if any records have been lost during processing

states.py

used for reference in iterator.py. this is a python dictionary to retrieve state abbreviations or full state names, depending on which is needed.

PARCEL UPDATE INSTRUCTIONS

1. Before running this script workflow, you will need to go into the parent folder, select all zips (ctrl + a), right-click and use 7-Zip or a similar application to extract all zips to current directory.

2. Run the iterator.py script by opening main.py and editing the required full path variables to point to the latest parcel update directory (data_dir) and your project working directory (output_workspace). These variables should be a path string with double backslashes (ie. G:\\Path\\TO\\YOUR\\DATA). Running the iterator.py will call all necessary functions for the script to complete so there is no further input required.

3. It will take some time, but when completed your output_workspace will have a featureclass for each state, plus the District of Columbia.

4. Right-click parcels.sde in the ArcGIS Pro catalog and choose Import --> Featureclasses or you can run a script to copy each one of the state parcel featureclasses from your local working directory (output_workspace) to the production parcels.sde geodatabase.