topic Re: VB formula to python in ArcGIS Pro Questions

VB formula to python

PeterVersteeg — Wed, 21 Nov 2018 17:23:46 GMT

Hello,

I am trying to get the tools Tree Points from LAS dataset and NAIP to work in ArcgisPro.

there is a calculate field with the formula "2 * Sqr (([Accum] * %Pixel Size% * %Pixel Size%) /3.14159265)"

how do i get this to work in ArcgisPro with python

Greetings,

Peter

Re: VB formula to python

curtvprice — Sat, 11 Dec 2021 17:19:05 GMT

I am not familiar with this tool. If it is published somewhere, please provide a link.

It looks like this is in Model Builder (with the model variable %Pixel Size% in it).

This should work okay. I used a code block.

# VBA Calculate Field expression
# "2 * Sqr (([Accum] * %Pixel Size% * %Pixel Size%) /3.14159265)"

# Calculate Field Python expression
f(!Accum!, %Pixel Size%)

# Calculate Field Python code block
import math
def f(accum, pix):
    return 2 * (((accum * pix * pix) / math.pi) ** 2‍‍‍‍‍‍‍‍‍‍)

# Use PYTHON_9.3‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: VB formula to python

PeterVersteeg — Wed, 21 Nov 2018 20:44:48 GMT

thank you for your help.

this is the tool

https://www.arcgis.com/home/item.html?id=d280e1c023084992b98088d9f14d3252

i still have a error:

file "<string>", line 1

f(!Accum!, %pixel size%)

syntax error: invalid systax

i am working in arcgis pro so python 3

Re: VB formula to python

DanPatterson_Retired — Wed, 21 Nov 2018 22:36:24 GMT

Are your fields names as such? and is %pixel size% title cased? (%Pixel Size%)?

Re: VB formula to python

curtvprice — Tue, 27 Nov 2018 20:51:15 GMT

I agree %Pixel Size% would be better as that's what the value field is named in the model.

You also may have to do this to force data type (VB kind of doesn't care)

f(!Accum!, float(%Pixel Size%))

The author of the tool unwisely left his email address so you may want to check with him and see if he any plans to upgrade to Pro. He may want a copy of your model!

Re: VB formula to python

ArthurCrawford — Tue, 26 Mar 2019 19:55:53 GMT

2 * math.sqrt (( !Accum! * %Pixel Size% * %Pixel Size%) / 3.14159265) - this is from the Pro version of Trees from Lidar.