Updatecursor returns with 'variable not defined'

Question

I am fighting a bit with the cursor function since this morning. Thanks to the help of the people here and some tutorials I found I got this far

import arcpy
arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Ecodis_clip_split" #set workspace to folder with values
value = [] #create list for the returning value of searchCursor
eco = arcpy.SearchCursor ("Anagance.shp", "", "", "area_ha", "") 
#search for the value in attributetable
for row in eco:
value.append(row) #write the value into the list
arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Wetland" 
#set workspace to folder with values
diss = arcpy.UpdateCursor ("diss_1.shp", "", "", "area_eco", "")
for row in diss:
 row.setValue(area_eco, row.getValue(value)) #identify all the rows and Update die field area_eco with the extracted value from the search cursor out of the list
 cursor.updateRow(row)
del eco
del diss

It bounces back with

area_eco is not defined

Which means - if I understood the concept of python correct - that this is not a variable. Ture, its my field which needs to updated. What am I doing wrong?

• dklassen: you need to have area_eco, typed as "area_eco", although I am not sure what you are doing with the row.getValue(value) portion of your statement, as the value variable is a list.
• four-eyes: My intention was to write the value I get from the searchCursor into a list and then write the Value from that list with the updateCursor into my rows. Not good?
• Erica: You can't do that without accessing the index value; see this StackOverflow question for how to do that. Also, you need to indent value.append(row) in your first for loop.
• four-eyes: Hello Erica, Thanks a lot for your answere but that StackOverflow Fred is beyond that what I understand. I added this to the Syntax row.setValue("area_eco", row.getValue(value[1])) to access the first index. But it says listindex out of range.
• dklassen: So to summarize what you are trying to do: you have 2 tables, and you are trying to take values from 1 table and populate the 2nd one with them? Correct? if so, what is the linking field - how do you know which "area_eco" to put in each row in the new table?

Answer 1

If there is only 1 value in your intial table, this will work, but if there are more, other code will be required.

import arcpy
arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Ecodis_clip_split" 
#set workspace to folder with values
# YOU DON'T need to do this for 1 value -- value = [] #create list for the returning value of searchCursor
## IF YOU HAVE MULTIPLE FIELDS - then you need to put them in a list or dictionary, and can reference them in the UpdateCursor.
eco = arcpy.SearchCursor ("Anagance.shp")
# loop through - this will assign the last AREA_ECO row value to the variable 'value' as you said you wanted.
for row in eco:
 value = row.AREA_ECO
arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Wetland" 
diss = arcpy.UpdateCursor ("diss_1.shp", "", "", "area_eco", "")
for row in diss:
 row.setValue("AREA_ECO", value)
 diss.updateRow(row)
del eco
del diss

• four-eyes: That works. I had to change that, I had to change the first value=row.AREA_ECO to ...row.area_ha. I have some questions regarding the code. I want to understand it that I do not have to come here the next time and ask 1000 questions. Can I shorten that diss = arcpy.UpdateCursor ("diss_1.shp", "", "", "area_eco", "") to diss = arcpy.UpdateCursor ("diss_1.shp")? And this diss.updateRow(row) is a thing that has to be written with the updateCursor? Otherwise it does not update it, even if we are setting the value here already? row.setValue("area_eco", value)
• dklassen: Also, if you know the value of "AREA_ECO" you can hard code it in, and skip the first search cursor.
• dklassen: correct - you can shorten that statement if you want, and it will work fine. The diss.updateRow(row) - this will update the row. You set the name of your cursor to be 'diss' that is why it looks like that, you can set it to xyz and it would then read... xyz.updateRow(row)
• four-eyes: ok. thanks. next step will be populate the field with different variables from different rows. but that will be next week :) Thanks for your help
• dklassen: to do that you need to have a corresponding field in the 2 feature classes.