topic Re: Model Builder Calculate Field Hangs in Geoprocessing Questions

Model Builder Calculate Field Hangs

PhilipRichardson — Thu, 30 Dec 2010 14:01:32 GMT

I have a built a model to add several fields to a table, then calculate the values from existing fields. This would appear to be a simple task, but model builder hangs after a few iterations. The problem seems to be with empty records. It reports an error for each empty record it encounters, then it just seems to lock up. I can accomplish the task in ArcMap by just telling Field Calculator to ignore the errors, but I was hoping to automate the task. I have also tried Pyton script, but it hangs just like Model Builder. Any thoughts?

Re: Model Builder Calculate Field Hangs

ChrisSnyder — Thu, 30 Dec 2010 15:51:32 GMT

As memory serves, this was a big issue with v9.2 (Field Calculator hangs)... I recall having this issue especially for large tables > 500k records.

The one guaranteed fix is to use an update cursor via a Python script in lieu of the CalculateField tool.

Re: Model Builder Calculate Field Hangs

LornaMurison — Tue, 04 Jan 2011 16:57:11 GMT

If the problem is only with empty records, could you just add a clause in your calculate field expression that deals with empty records. i.e. if Field1 = "" then Field2 = "" (or if Field1 isnull ...)?

Re: Model Builder Calculate Field Hangs

PhilipRichardson — Thu, 06 Jan 2011 20:07:48 GMT

You are correct. The problem exists with nulls and empty records. I just figured this out today, by selecting only records with values before the field calculation. It adds some steps in the model, but it now works.

Re: Model Builder Calculate Field Hangs

PhilipRichardson — Tue, 01 Feb 2011 20:54:27 GMT

Unfortunately, the model is not working like I originally had hoped. The difficulty is with zero length string records. I have been trying to get a VB expression that would identify zero-length records. If a zero-length record exists, then populate the new field with a null, else calculate the new record. The model converts a date expressed as a string to an actual date record.

Re: Model Builder Calculate Field Hangs

PhilipRichardson — Wed, 02 Feb 2011 19:29:54 GMT

This is what I decided to do. Instead of populating the new field with nulls, I used a date 1/1/1900, which I can use as a flag later. To handle the zero-length string problem, I needed a VB script to recognize a zero-length cell, and substitute a date 1/1/1900.

dim pstart1 as string
dim pstart2 as string
pstart1 = [Date_Start]
if pstart1 = "" then
pstart2 = "1900-01-01"
else
pstart2 = pstart1
end if

[Date_Start] is the original field with dates expressed as a string. The field calculator converts [Date_Start] to [New_Date], which is date format. [New_Date] = pstart2