calculate field in ARCGIS

MRAB google at mrabarnett.plus.com
Thu Apr 9 23:58:05 CEST 2009


Lydia wrote:
> Thanks for the suggestion.
> 
> But I guess under Python this doesn't work. I tried putting the code in 
> different ways. But still not worked.
> 
> codeblock = "def codefun(code): \\
>                            if code == 0: \\
>                                return \"B\"  \\
>                            else: return \"\" "
> 
> 
You might also want to try a triple-quoted string, which makes it
clearer:

codeblock = """def codefun(code):
     if code == 0:
         return "B"
     else:
         return ""
"""

> ----- Original Message ----- From: "Chris Rebert" <clp2 at rebertia.com>
> To: "Lydia" <cssaua at hotmail.com>
> Cc: <python-list at python.org>
> Sent: Thursday, April 09, 2009 1:55 PM
> Subject: Re: calculate field in ARCGIS
> 
> 
> On Thu, Apr 9, 2009 at 12:42 PM, Lydia <cssaua at hotmail.com> wrote:
>> Hi Python users,
>>
>> I ran into a problem with python coding in ARCGIS. Does anybody have the
>> experience in dealing with this?
>>
>> I need to calculate NEWFIELD based on OLDFIELD under condition: if 
>> OLDFIELD
>> == 0 then return string "B" otherwise return "".
>>
>> codeblock = "def codefun(code): if code == 0: return \"B\" else: 
>> return \"\"
>> "
>>
>> gp.CalculateField_management("INFILE", "OLDFIELD", "codefun(!NEWFIELD!",
>> "PYTHON", codeblock)
>> I got error:
>>
>> RuntimeError:
>> exceptions.SyntaxError: invalid syntax (line 1)
>> Failed to execute (CalculateField).
> 
> Might I recommend you try using the multiline equivalent (assuming
> ArcGIS supports C-style escape sequences):
> 
> codeblock = "def codefun(code):\n\tif code == 0:\n\t\treturn
> \"B\"\n\telse:\n\t\treturn \"\" "
> 
> Cheers,
> Chris
> 




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