ArcGIS Python Script, Calculate Field

Question

I am trying to write a Python Script for ArcGIS 10.2.

#import system modules 
import arcpy 
import math 
from arcpy import env 

#Set environment options 
env.workspace="C:/Users/el/ac/script1" 

# Set local variables 
inFeatures = "line2.shp" 
fieldName = "angle1" 
expression = "GetAzimuthPolyline(!Shape!)" 
codeblock = """import math 
def GetAzimuthPolyline(shape): 
    radian = math.atan((shape.lastpoint.x - shape.firstpoint.x)/(shape.lastpoint.y - shape.firstpoint.y)) 
    degrees = radian * 180 / math.pi 
    return degrees""" 


# Execute AddField 
arcpy.AddField_management(inFeatures, fieldName, "SHORT") 
#print "Field has been added." 

# Execute CalculateField 
arcpy.CalculateField_management(inFeatures, fieldName, "GetAzimuthPolyline(!Shape!)", "PYTHON", codeblock)

Field was added, but the result is not calculated and is not writing into the field. But, if I write the code block in Calculate field in ArcMap, field calculates correctly. Why?

Code was amended. But if I run the script:

Traceback (most recent call last):
  File "C:\Users\el\ac\script1\scr1.py", line 35, in <module>
arcpy.CalculateField_management(inFeatures, fieldName, "GetAzimuthPolyline(!Shape!)", "PYTHON", codeblock)
  File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\management.py", line 3354, in CalculateField
    raise e
ExecuteError: ERROR 000539: Error running expression: GetAzimuthPolyline(GPVARIANTOBJECT0) 
Traceback (most recent call last):
  File "<expression>", line 1, in <module>
  File "<string>", line 3, in GetAzimuthPolyline
AttributeError: 'str' object has no attribute 'x'

Answer 1

You're using an expression type of 'PYTHON', but to support the calculation you're trying, you need to use 'PYTHON_9.3'.

Answer 2

Since you're doing the calculation from within a Python script anyway (as opposed to the Field Calculator GUI or a Model Builder model), I would rewrite the code using an arcpy.da.UpdateCursor to avoid the awful code-within-a-string that's required for a CalculateField_management() codeblock:

#import system modules 
import arcpy 
import math 
from arcpy import env 

#Set environment options 
env.workspace="C:/Users/el/ac/script1" 

# Set local variables 
inFeatures = "line2.shp" 
fieldName = "angle1"

def GetAzimuthPolyline(shape): 
    radian = math.atan((shape.lastPoint.x - shape.firstPoint.x)/(shape.lastPoint.y - shape.firstPoint.y)) 
    degrees = radian * 180 / math.pi 
    return degrees 

# Execute AddField 
arcpy.AddField_management(inFeatures, fieldName, "SHORT")
#print "Field has been added." 

# Calculate field with arcpy.da.UpdateCursor
with arcpy.da.UpdateCursor(inFeatures, ['SHAPE@', fieldName]) as cursor:
    for row in cursor:
        row[1] = round(GetAzimuthPolyline(row[0]))  # Round to integer, because field is "SHORT"
        cursor.updateRow(row)

Answer 3

As @Erica said, there is an indentation error in your code block. I'm surprised it isn't throwing a Syntax Error when you try to run calculate field. In any case,

codeblock = """import math 
def GetAzimuthPolyline(shape): 
    radian = math.atan((shape.lastpoint.x - shape.firstpoint.x)/(shape.lastpoint.y - shape.firstpoint.y)) 
degrees = radian * 180 / math.pi 
return degrees""" 

should be

codeblock = """import collections
import math

pt_ = collections.namedtuple("pt", "x y")

def toPoint(shapePT):
    if isinstance(shapePT, basestring):
        return pt(*map(shapePT.split()[:2]))
    return shapePT

import math 
    def GetAzimuthPolyline(shape):
        first_point = toPoint(shape.firstpoint)
        last_point = toPoint(shape.lastpoint)
        radian = math.atan((last_point.x - first_point.x)/(last_point.y - first_point.y)) 
        degrees = radian * 180 / math.pi 
        return degrees
    return shapePT"""