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Python Functions?

Question asked by Playa on Jul 6, 2015
Latest reply on Jul 9, 2015 by bixb0012

I've been writing Python scripts for a while now, and when a colleague of mine viewed my code, he cringed that it wasn't structured into Python Functions. I'd like some advice from the ESRI community in how I could structure my Python scripts into functions\modules that will make it easier to reuse and call within new scripts. I've attached one of my Python scripts that uses ArcPy and ArcHydro Functions.


Created on May 20, 2015
@author: PeterW
# import system modules and site packages
import os
import arcpy
import ArcHydroTools
# check out Spatial Analyst Extension
# set environment settings
arcpy.env.overwriteOutput = True
# set input and output arguments
raw = r"F:\Projects\2015\G111443\ArcHydro\Methodology_Models\Section03\Sect3A\DEM04\raw"
rasWs = r"F:\Projects\2015\G111443\ArcHydro\Methodology_Models\Section03\Sect3A\Layers04"
outWs = r"F:\Projects\2015\G111443\ArcHydro\Methodology_Models\Section03\Sect3A\Model04.gdb"

# ArcHydro variables
fill_sinks = os.path.join(rasWs, "fil")
flow_dir = os.path.join(rasWs, "fdr")
flow_acc = os.path.join(rasWs, "fac")
streams = os.path.join(rasWs, "str")
stream_seg = os.path.join(rasWs, "strlnk")
catchment_grid = os.path.join(rasWs, "cat")
catchment_poly = os.path.join(outWs, "Layers","Catchment")
drainage_line = os.path.join(outWs, "Layers", "DrainageLine")
adj_catch = os.path.join(outWs, "Layers", "AdjointCatchment")

    # calculate the fill sinks
    arcpy.AddMessage("Processing Fill Sinks")
    ArcHydroTools.FillSinks(raw, fill_sinks)
    # calculate the flow direction
    arcpy.AddMessage("Processing Flow Direction")
    ArcHydroTools.FlowDirection(fill_sinks, flow_dir)
    # calculate the flow accumulation
    arcpy.AddMessage("Processing Flow Accumulation")
    ArcHydroTools.FlowAccumulation(flow_dir, flow_acc)
    # calculate the maximum flow accumulation
    arcpy.AddMessage("Processing Flow Accumulation Maximum")
    maxcellsResult = arcpy.GetRasterProperties_management(flow_acc, "MAXIMUM")
    maxcells = maxcellsResult.getOutput(0)
    print maxcells
    # calculate the stream threshold number of cells
    arcpy.AddMessage("Processing Stream Threshold")
    stream_threshold_numcells = (int(maxcells)*0.25/100)
    print stream_threshold_numcells
    # calculate the stream definition
    arcpy.AddMessage("Processing Stream Definition")
    ArcHydroTools.StreamDefinition(flow_acc, stream_threshold_numcells, streams)
    # calculate the stream segmentation
    arcpy.AddMessage("Processing Stream Segmentation")
    ArcHydroTools.StreamSegmentation(streams, flow_dir, stream_seg)
    # calculate the catchment grid delineation
    arcpy.AddMessage("Processing Catchment Grid Delineation")
    ArcHydroTools.CatchmentGridDelineation(flow_dir, stream_seg, catchment_grid)
    # calculate the catchment polygons from the catchment grid
    arcpy.AddMessage("Processing Catchment Polygons")
    ArcHydroTools.CatchmentPolyProcessing(catchment_grid, catchment_poly)
    # calculate the drainage lines from the stream segmentation grid
    arcpy.AddMessage("Processing DrainageLines")
    ArcHydroTools.DrainageLineProcessing(stream_seg, flow_dir, drainage_line)
    # calculate the adjoint catchment polygons
    arcpy.AddMessage("Processing Ajdoint Catchments")
    ArcHydroTools.AdjointCatchment(drainage_line, catchment_poly, adj_catch)
    arcpy.AddMessage("Completed Processing ArcHydro Main Model")


Any advice and assistance will be appreciated.




Peter Wilson