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'

• Erica: Check the indentation: are all the lines of the codeblock statement indented or not? (It might be correctly indented in your actual code, but was lost when pasting.)
• Elshurito: i'm sorry. I lost actual code when pasting
• dango: I have always had trouble with CalculateField run from a python script so I prefer to use cursors instead .... could this be an option for you?
• nmpeterson: Might it be a problem with case-sensitivity? Try shape.firstPoint.X, shape.firstPoint.Y, shape.lastPoint.X and shape.lastPoint.Y
• Paul: Instead of using calculate field, you might want to investigate cursors in the data access module. Don't need to worry about formatting all this as a multi-line string.

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'.

• F_Kellner: DWYnne is correct. I was able to get the function to work when I changed it "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""" 

• Elshurito: Thank You, but I get the same error as in the beginning. I think the problem in line: arcpy.CalculateField_management(inFeatures, fieldName, "GetAzimuthPolyline(!Shape!)", "PYTHON", codeblock)