topic Re: Function to delete records in Python Questions

Function to delete records

LianaSmith — Thu, 19 May 2016 17:45:27 GMT

I need a small code in python that will delete records that have empty value in a specific field of the layer. The name of the feature class is WCSCustomer and the name of the field is GROUTE

Re: Function to delete records

AdrianWelsh — Thu, 19 May 2016 17:51:36 GMT

Hi Liana,

Take a look at this thread:

Delete Rows where value is Null

I believe this will have the solution that you need.

Re: Function to delete records

LianaSmith — Thu, 19 May 2016 17:55:32 GMT

Thanks, Adrian. I have just empty value, not Null.. I am not sure if I can change the script for that myself..

Re: Function to delete records

AdrianWelsh — Sat, 11 Dec 2021 06:26:18 GMT

maybe try

import arcpy

fc = r'C:\tmp\Test.gdb\WCSCustomer'
field = "GROUTE"
whereClause = field + ' = ""'

updCurs = arcpy.UpdateCursor(fc, whereClause)
for row in updCurs:
    if not row.getValue(field):
        updCurs.deleteRow(row)

Re: Function to delete records

MitchHolley1 — Thu, 19 May 2016 17:58:42 GMT

Use None instead of "Null"

for x in this:

if x is None:

delete that stuff

Re: Function to delete records

LianaSmith — Thu, 19 May 2016 18:16:34 GMT

Adrian,

I tried to ran it and I get an exception..

Re: Function to delete records

AdrianWelsh — Sat, 11 Dec 2021 06:26:21 GMT

yeah, an issue with the SQL statement.

Since it's in a file geodatabase, could you just use the Null value approach?

import arcpy


fc = r"C:\tmp\Test.gdb\WCSCustomer"
field = "GROUTE"
whereClause = field + " IS NULL"


updCurs = arcpy.UpdateCursor(fc, whereClause)
for row in updCurs:
    if not row.getValue(field):
        updCurs.deleteRow(row)

Or use Mitch's example of if x is none, etc....

Re: Function to delete records

DanPatterson_Retired — Thu, 19 May 2016 20:13:46 GMT

or alternately

do the row.getvalue or row[index number] thing ( we will call it x using Mitch's designation)

then....

if x in [None,""]:

delete stuff

The rationale is that an empty records is going to show <null> in the table, but python returns None and shapefiles store "" and other stuff stores one of those two (if memory serves). The nice thing is you can add anything you want to the list. the python 'isinstance' can also be used, but then you have to remember the class and None is a NoneType or which there is only one instance of that class.

Re: Function to delete records

curtvprice — Sat, 11 Dec 2021 06:26:23 GMT

In this whole thread I don't see the full example.

My code will zap the row if the field contents is spaces, empty string, or Null.

fc = r"C:\tmp\Test.gdb\WCSCustomer"
field = "GROUTE"
with arcpy.da.UpdateCursor(fc, field) as rows:
    for row in rows:
        try:
            val = row[0].strip()
        except:
            val = row[0]
        if val in ["", None]:
            rows.deleteRow(row)

Re: Function to delete records

JoshuaBixby — Fri, 20 May 2016 21:04:27 GMT

I assume you are working with text fields since you are talking about empty being different than Null (or None in Python). When working with text fields, just be aware there are some characters and numerous control characters that don't display (the field will look empty in ArcMap/ArcCatalog) but prevent !field! == "" from being True.

It might be worth looking over the following discussion: I am trying to calculate a field where i want to exclude any null values. For example. Field calulate field X with any value that is not null from field Y. I have been messing with python, but just can not seem to get this to run properly.

Re: Function to delete records

curtvprice — Sat, 11 Dec 2021 06:26:26 GMT

I found code to strip all non printables on StackOverflow.

def stripper(s):
    return "".join(i for i in s if ord(i)<127 and ord(i)>32)

fc = r"C:\tmp\Test.gdb\WCSCustomer" 
field = "GROUTE" 
with arcpy.da.UpdateCursor(fc, field) as rows: 
    for row in rows: 
        try: 
            val = stripper(s)
        except: 
            val = row[0] 
        if val in ["", None]: 
            rows.deleteRow(row)

Re: Function to delete records

DanPatterson_Retired — Sun, 22 May 2016 03:03:44 GMT

with the unicode encoding cavaet is people move closer to python 3. Make sure you read that full thread, it is interesting... a "space" is much like "nothing"..it comes in many forms