arcgis-10.1arcgis-desktopfield-calculatorpython
I have two fields (STREET1 & AKA_STREET_TEST1).
I'm having a problem creating a simple IF THEN Python statement in the Field Calculator box. I've been searching the threads for a similar example but to no avail. Basically the formula would work something like this.
If STREET1 contains "AVENUE", calculate AKA_STREET_TEST1 to "AVE",
ELSE leave it blank
(example below)
Below is my feeble attempt at creating the if-then statement.
You could create a Python function for the field calculator using the logic below (using the first record as an example:
>>> a = "EW 140 Rd MF 71" # your primary field
>>> b = str(71.6) # your secondary field
>>> a.replace(a.split(" ")[-1], b) #replace the last entry in the list
'EW 140 Rd MF 71.6'
Or as a def, this might get your further (this example assumes that you are replacing the last entry in string.
def replace_item(primary, secondary):
'''replace a substring in the primary field with that found in the secondary field:
string field assumed for primary'''
a = primary.replace(primary.split(" ")[-1], str(secondary))
return a
if __name__ == "__main__":
primary = "EW 140 Rd MF 71"
secondary = 71.6
print replace_item(primary, secondary)
and you can run it in standalone mode for testing as shown
EDIT For clarification, when one is doing calculations in the field calculator using Python code blocks, the above code, up to and including the "return a" line is all that is needed. The rest is for running the code as a standlone program in something like Pythonwin. So that code goes in the code block when you toggle on the "show code block" checkbox. To use the above function, make the destination field active and specify the function with the input fields in the expression box. For example:
replace_item(!PRIMARYFLD!, !SECONDARYF!)
would be used assuming the two obviously named fields listed above (ie. PRIMARYFLD and SECONDARYFLD) if they existed in your table. The help files in ArcGIS also indicate that field names must be enclosed in exclamation marks, !. More information can be found in the online help for those wishing to use Python code blocks with the field calculator.
If I understand correctly, you might try something like the replace() function:
replace([FieldName], "Old Value", "New Value")
!FieldName!.replace("Old Value", "New Value")
Here is a link to the ESRI support page for it: http://support.esri.com/en/knowledgebase/techarticles/detail/20119
Best Answer
A couple things to note:
Your code block is currently taking two arguments, but you really only need to take one.
AKA_STREET_TEST1is the result you want, not something thatCalc()will consider when calculating. So your expression should beCalc(!STREET1!)-- because you want the functionCalcto do something using the information from fieldSTREET1, and that value will then be assigned toAKA_STREET_TEST1.You can use a simple, one-line operation with Python's
string.replacefunction, which essentially incorporates your if-then logic automatically. IfAVENUEis in the string, it will be replaced withAVE. IfAVENUEisn't there, it returns nothing and should leave the attribute empty.