This python script and ArcGIS Pro script tool takes the line bearing of every street and visualizes the proportion going in certain directions via a polar histogram and shapefile outputs. This is applicable for analyzing street network orientations. A city with a perfect grid-iron street form will be represented by a polar histogram with a cross shape (all streets go in one of two directional pairs). The opposite, a city with streets' endpoints' bearing going in all different directions would be represented by a polar histogram with bars creating a rounder shape. The closer to a circular form the polar histogram's bars are, the closer the city is to equal proportions of streets going in every direction.
Make sure the following modules are installed: arcpy, geopandas, plotly.
The format is as follows: Python Object(Script Tool Parameter): Description
zones (Zones Feature Class): The polygon boundaries that will be used to delineate the area that each polar histogram is describing. The test data uses Tampa's Planning Districts, boundaries taken from the City of Tampa GeoHub.
zone_name_field (Zone Name Field): This is the name of the field that describes each zone, as found in the feature class's attribute table. The test data will use the 'NAME' field as a descriptor, but city/neighborhood names could also be used depending on the zone feature class.
streets (Streets Feature Class): The streets to be processed for their orientation. The test data uses the City of Tampa geodata hub's Road Centerlines.
output_folder_name (Output Folder Name): Where the outputs will be stored. If there is not an existing folder already, a new one will be created in the location specified.
Output Path > polar_histograms >
- Polar Histogram JPGs will be created inside this folder.
Output Path > Clipped_Streets >
- Individual shapefiles of the streets layer clipped to each zone.
- Python Modules: arcpy (to run geoprocessing), plotly (to create the polar histograms), and geopandas (here, solely to read the shapefile as a GDF before creating the polar histogram with plotly)
- Multiprocessing: each "zone" (city, neighborhood, zip code, etc) is sent to a CPU as a 'task'
- Creating a ArcGIS Toolbox
Either download and run the arcpy, hardcoding the input variables, or use the ArcGIS script tool. This achieves the same output within the ArcGIS Pro application. Ensure that the bin_key.csv is in the local drive to correctly run.
- Download st_orientationsample_data.zip and extract the folders. This contains the two shapefiles required to run the script, the zones and streets shapefiles, and the bin key csv.
- Set the working directory to the correct location locally (line 44).
- Run the script and find your outputs in the output folder (line 62)!
Data from the City of Tampa GeoHub (CC0 1.0 License)