topic Re: Question on ´GIS Tutorial for Python Scripting´ working with cursorsl in Python Questions

Question on ´GIS Tutorial for Python Scripting´ working with cursorsl

Ericvan_Rees — Tue, 24 Feb 2015 21:35:39 GMT

Hello,

I´m trying to work my way through the ´GIS Tutorial for Python Scripting´ by David Allen. Working with cursors (Tutorial 2.3) is giving me a hard time as there seem to be a number of ways to approach this subject, but I can´t make any sense of them. What confuses me most is the numbering in the syntax. Can anybody helmp me with Exercise 2.3? The problem seems to be a non-defined cursor name, but I´m lost here. This is the code I´ve come up with so far:

import arcpy

from arcpy import env

env.workspace = r"C:\EsriPress\GISTPython\Data\City of Oleander.gdb"

env.overwriteOutput = True

updateFC = "StreetLights"

with arcpy.da.UpdateCursor("StreetLights",["TYPE", "Buffer"]) as cursor:

for row in cursor:

TYPE = row[0]

Buffer = row[1]

if TYPE == "MV":

Buffer = 125

else:

Buffer = 200

cursor.updateRow(row)

print "All done updating"

del cursor

del row

Re: Question on ´GIS Tutorial for Python Scripting´ working with cursorsl

XanderBakker — Sat, 11 Dec 2021 12:06:22 GMT

A few errors in the code.

row[1] is the buffer value you try to assign, so you should write to it, without it, it doesn't make sense to update the row, since nothing changes
delete the cursor and row outside the with statement, otherwise you are "cutting the branch you're sitting on"

import arcpy
from arcpy import env
env.workspace = r"C:\EsriPress\GISTPython\Data\City of Oleander.gdb"
env.overwriteOutput = True
updateFC = "StreetLights"
with arcpy.da.UpdateCursor(updateFC, ["TYPE", "Buffer"]) as cursor:
    for row in cursor:
        TYPE = row[0]
        if TYPE == "MV":
            row[1] = 125
        else:
            row[1] = 200
        cursor.updateRow(row)
del cursor, row

Re: Question on ´GIS Tutorial for Python Scripting´ working with cursorsl

Ericvan_Rees — Tue, 24 Feb 2015 21:58:19 GMT

Hello Xander,

thanks for your clear explanation, this is very helpful.

Eric