Using Python Function in Field Calculator to find numbers

Question

Disclaimer, I am terrible at writing my own functions especially in the field calculator. I have an address field (Address) with records that are missing street numbers. I would like to find these records, skip over them, and populate a field (Number) with the first element of the records that do have a street number. I would like to do this in the field calculator if possible (ArcMap 10.2.2, Basic).

Here's what I got so far:

def findNumbers(Address):
 if Address.split(" ")[0].isalpha():
 pass
 elif int(Address.split(" ")[0]) >= 0:
 Number = Address.split[0]
Number = 
def findNumbers(!Number!)

• geoJshaun: I see, but It's in the field calculator which requires a python syntax that is specific to calculations done in ArcMap. How would a non ArcMap python programmer be able to answer this?

Answer 1

Regular expressions are nice for extraction.

import re
def extract(s): 
 num = re.search('^\d+', s) # find all leading digits
 if num is None:
 return None
 else:
 return int(num.group())

• FelixIP: import before def ?
• Paul: @FelixIP, ideally yeah you would import in the python window.
• Paul: @FelixIP, never realized the code block could have more than a def statement. It only runs that initially (e.g import time;time.sleep(5) adds only 5s to runtime not 5x#rows). Good to know!
• FelixIP: @Paul I take it to extremes sometimes, gis.stackexchange.com/questions/193681/…
• Paul: @FelixIP, that's awful, haha. +1 though for abusing field calculator.

Answer 2

This question is most certainly a duplicate, but anyway I'd use:

def getNumber(aString):
 aList=aString.split();n=len(aList)
 if n>1:
 try: aNumber= int(aList[0]);return aNumber
 except: return -1
 else: return -1
#-----------------------
getNumber(!address!)

providing there are now houses like 23B, i.e. non-numeric suffix is absent

• geoJshaun: Thank Felix. I did a search and didn't find anything, but I digress.