topic Re: GIS tutorial for Python Scripting written by David Allen in Python Questions

GIS tutorial for Python Scripting written by David Allen

Jeremiah_OlatundeGbolagun — Thu, 18 Sep 2014 01:05:22 GMT

Please let me know if the below code is right or not. if it is wrong can you please correct it for me.

I changed the below code from the above titled book during learning Tutorial 1, which was titled "Use Python in the Label Expression dialog box". I am using ArcGIS 10.1 but the tutorial used ArcGIS 10.2.

This is the original code from the text book.

def FindLabel ( [OwnerName] 😞

rawName = [OwnerName]

commaNum = rawName.find(",")

formatName = rawName[commaNum+2:] + " " + rawName[:commaNum]

return formatName

When I run this above code I have this error "SyntaxError: invalid syntax (<string> , line 4"

Can you please let me know the right code to use.

I modify it to below code but still experience another error.

def FindLabel ( [OwnerName] 😞

rawName = [OwnerName]

commaNum = rawName.find(",")

formatName = rawName(commaNum[2:]) + " " + rawName(commaNum[0:]

return formatName

Regards,

Jeremiah.

Re: GIS tutorial for Python Scripting written by David Allen

curtvprice — Thu, 18 Sep 2014 06:20:38 GMT

I bet this doesn't work because within the label engine brackets are interpreted as field names. The examples in the help do not use brackets in the python examples and I think that is why! My guess is Mr. Allen tested the code at the Python prompt (not inside the label engine) and called it good, though I could be wrong.

Here's a method that avoids the brackets and takes advantage of the split, join, and reverse list methods. Neat, huh?

def FindLabel ( [OwnerName] ):
  rawName = [OwnerName] # "Last,First"
  names = rawName.split(",") # ["Last", "First"]
  formatName = " ".join(names.reverse()) # "First Last"
  return formatName

Re: GIS tutorial for Python Scripting written by David Allen

MichaelAugust — Thu, 18 Sep 2014 15:59:25 GMT

def FindLabel ( [OwnerName] 😞

rawName = [OwnerName]

commaNum = rawName.find(",")

formatName = rawName[:commaNum+2:] + " " + rawName[:commaNum]

return formatName

do you need to add a colon before the first commaNum above?

Re: GIS tutorial for Python Scripting written by David Allen

ChristopherLopez — Thu, 18 Sep 2014 18:56:55 GMT

Your first set of code worked for me, I just copied and pasted what you had. Just be sure you have advanced checked and your parser is set to Python.

Re: GIS tutorial for Python Scripting written by David Allen

Jeremiah_OlatundeGbolagun — Thu, 18 Sep 2014 22:18:36 GMT

No I do not think so. This code was copied from the GIS tutorial for Python

Scripting tutorial 1 example. Please note that the code is to be run ArcGIS

10.2. But I ran the code on ArcGIS 10.1 and it gave me error that I sent to

the GeoNet forum site.

Re: GIS tutorial for Python Scripting written by David Allen

curtvprice — Fri, 19 Sep 2014 18:33:18 GMT

Pretty strange, sir, your code works for me (10.1 SP 1).

I agree with the advice above to click the advanced checkbox and set the parser to Python before pasting the code.

Re: GIS tutorial for Python Scripting written by David Allen

DavidAllen — Tue, 23 Sep 2014 13:05:37 GMT

Hey Jeremiah, Glad to know that you're working through the book and I'm sorry that you got hung up on this one.

There may be some differences in how the concatenations are handled between 10.1 and 10.2. They did a rewrite on that part of ArcPy to handle some issues with commas, quotes, and such. You'll find a part in the book later where I address that.

Try making a variable for the comma position you want in the first slicing action and see if that helps:

def FindLabel ( [OwnerName] 😞

rawName = [OwnerName]

commaNum = rawName.find(",")

commaNumTwo = commaNum + 2

formatName = rawName[commaNumTwo:] + " " + rawName[:commaNum]

return formatName

Not all the Python code errors you get are specifically from the Python error generator - some come from ArcPy and therefore are subject to change. So I try to take any statement where I've some something complex and break it into simple terms and try again. When I've isolated the error, then I can go back and make my code more concise.

Let me know how that goes.

David Allen

Re: GIS tutorial for Python Scripting written by David Allen

Jeremiah_OlatundeGbolagun — Wed, 24 Sep 2014 02:04:17 GMT

Hi David,

Thank you for responding to the Python error I posted on the Geonet forum.

Please note that the code written in your book worked well when I rerun it.

But I later discovered the cause of the error which was due to

inappropriate use of the code indentation. For example, if you do not use

the appropriate number of spaces as you have written in the book it will

result into error. if you checked the error that I posted you will

understand what I meant.

Regards,

Jeremiah.

Re: GIS tutorial for Python Scripting written by David Allen

DavidAllen — Wed, 24 Sep 2014 13:10:25 GMT

Should have gone with the odds and said indentions …

Ya know, the only thing harder than debugging your code is debugging someone else’s code!!

Let me know if you have any other issues. The exercises are challenging and the steps aren’t shown so if you get stuck on one of those I can send the key.

David

Re: GIS tutorial for Python Scripting written by David Allen

curtvprice — Wed, 24 Sep 2014 20:17:55 GMT

Interesting, you indented it correctly in your post! FYI here is how to post code here:

Posting Code blocks in the new GeoNet‌

Re: GIS tutorial for Python Scripting written by David Allen

JaredStewart — Wed, 24 Sep 2014 22:01:32 GMT

Hi Curtis,

Clicking on your blog link directs me to a page with the following message:

Access to this place or content is restricted. If you think this is a mistake, please contact your administrator or the person who directed you here.

Re: GIS tutorial for Python Scripting written by David Allen

curtvprice — Thu, 25 Sep 2014 05:30:14 GMT

Thanks for letting me know... I moved my blog out of the python space to my personal space. It should be accessible by everyone now.

Re: GIS tutorial for Python Scripting written by David Allen

JaredStewart — Thu, 25 Sep 2014 17:12:25 GMT

Excellent, thank you! That is a very handy tip!