topic Re: Field Calculator - field values as variables in Pre-Logic Script Code in Python Questions

Field Calculator - field values as variables in Pre-Logic Script Code

PSArcOnlinePSArcOnline — Tue, 08 Jan 2013 10:51:47 GMT

Hello, i need a litte help. Maybe just a syntax error.

I want to do some little vector math.

Pre-Logic Script Code

import sys def GetVector(shape):   x0 = 1  y0 = 2  x1 = 3  y1 = 4  a = [x0, y0]  b = [x1, y1]  vecsum = [a[0]+b[0], a[1]+b[1] ]  return vecsum[1]

Assignment Code

GetVector( !Shape!)

This works. But i want to use field values, stored in the shape file, for the variables. As one example i tried this:

Pre-Logic Script Code

import sys def GetVector(shape):   x0 = !xorigin!   y0 = 2  x1 = 3  y1 = 4  a = [x0, y0]  b = [x1, y1]  vecsum = [a[0]+b[0], a[1]+b[1] ]  return vecsum[1]

which gives a syntax error. What is wrong? In the Shape file there is a field named "xorigin" (type double) with a value of 3773506,87592.

Re: Field Calculator - field values as variables in Pre-Logic Script Code

MathewCoyle — Tue, 08 Jan 2013 12:27:19 GMT

You have to pass it from the calculation expression as a variable.

def GetVector(shape, xorigin):     x0 = xorigin     y0 = 2     x1 = 3     y1 = 4     a = [x0, y0]     b = [x1, y1]     vecsum = [a[0] + b[0], a[1] + b[1]]     return vecsum[1]

GetVector(!Shape!, !xorigin!)

Re: Field Calculator - field values as variables in Pre-Logic Script Code

PSArcOnlinePSArcOnline — Wed, 09 Jan 2013 09:58:07 GMT

Thanks, that did the trick.