Sinuosity Python Script

Question

To start, I'm very new to scripting. On ArcGIS, there is a python script for a Sinuosity tool http://resources.arcgis.com/en/help/main/10.1/index.html#//001500000022000000

I've tried it and it didn't work and so I did some changes to it and while it runs without error, I get no output in my attribute table. What are my errors? What can I do/add to this script to get an output?

import arcpy
import math
import os
#overwrite existing output
arcpy.env.overwriteOutput = True
class Toolbox(object):
 def __init__(self):
 self.label = "Sinuosity toolbox"
 self.alias = "sinuosity"
 # List of tool classes associated with this toolbox
 self.tools = [CalculateSinuosity] 
class CalculateSinuosity(object):
 def __init__(self):
 self.label = "Calculate Sinuosity"
 self.description = "Sinuosity measures the amount that a river " + \
 "meanders within its valley, calculated by " + \
 "dividing total stream length by valley length."
 def getParameterInfo(self):
 #Define parameter definitions
 # Input Features parameter
 in_features = arcpy.Parameter(
 displayName="Input Features",
 name="in_features",
 datatype="GPFeatureLayer",
 parameterType="Required",
 direction="Input")
 in_features.filter.list = ["Polyline"]
 # Sinuosity Field parameter
 sinuosity_field = arcpy.Parameter(
 displayName="Sinuosity Field",
 name="sinuosity_field",
 datatype="Field",
 parameterType="Optional",
 direction="Input")
 sinuosity_field.value = "sinuosity"
 # Derived Output Features parameter
 out_features = arcpy.Parameter(
 displayName="Output Features",
 name="out_features",
 datatype="GPFeatureLayer",
 parameterType="Derived",
 direction="Output")
 out_features.parameterDependencies = [in_features.name]
 out_features.schema.clone = True
 parameters = [in_features, sinuosity_field, out_features] 
 return parameters
 def isLicensed(self): #optional
 return True
 def updateParameters(self, parameters): #optional
 if parameters[0].altered:
 parameters[1].value = arcpy.ValidateFieldName(parameters[1].value,parameters[0].value)
 return
 def updateMessages(self, parameters): #optional
 return
 def execute(self, parameters, messages):
 in_features = parameters[0].valueAsText
 fieldName = parameters[1].valueAsText
 if fieldName in ["#", "", None]:
 fieldName = "sinuosity"
 arcpy.AddField_management(inFeatures, fieldName, 'DOUBLE')
 expression =
 def getSinuosity(shape):
 length = shape.length
 d = math.sqrt((shape.firstPoint.X - shape.lastPoint.X) ** 2 +
 (shape.firstPoint.Y - shape.lastPoint.Y) ** 2)
 return d/length
 arcpy.CalculateField_management(in_features,fieldName,'getSinuosity(!shape!)','PYTHON_9.3')

Answer 1

Look at the help page What is a Python toolbox? and then scroll to the bottom of the page and look at the code sample. Note how the the function getSinuosity which is the expression is enclosed in 3 single quotes. Your code is not and you do not include it as a parameter in the CalculateField line.