Using Update Cursor gives IndexError: list assignment index out of range?

Question

I am trying to use an update cursor and receiving an error. I'm not very familiar with using cursors, so please bear with me. I am trying to write a 1 or 0 to a field, based on a condition. The error I am receiving is:

IndexError: list assignment index out of range.

I have googled around and have seen solutions, but I'm still not understanding why its throwing an error.

#Define Environments
rasters = r"C:\Data.gdb"
points = r"C:\Data.gdb\Points"
#Set workspace
arcpy.env.workspace = rasters
arcpy.env.overwriteOutput = True
# Get a list of the rasters in the workspace 
rasters = arcpy.ListRasters()
# Loop through the list of rasters 
for inRaster in rasters: 
 print str("Processing " + inRaster)
 rastername = str(inRaster)
 fieldname = str(inRaster + "_perf_flag")
 # Add surface information to Well FC
 arcpy.AddSurfaceInformation_3d(points,inRaster , "Z", "LINEAR")
 print "Formation Depth Added"
 # Create positive values from SS values
 arcpy.CalculateField_management(points, "Z", '!Z!*-1', "PYTHON")
 print "Depth Values Made Positive"
 # Add new field name for perf flag
 arcpy.AddField_management(points, fieldname, "LONG", 9, "", "", fieldname, "NULLABLE", "NON_REQUIRED")
 print "Flag Field Added"
 # Raname Z field as formation grid name
 arcpy.AlterField_management(points, 'Z', rastername, rastername)
 print "Field Altered"
 # Calculate if well was perfed in the formation - Flag 1 as yes - Flag 0 as no
 with arcpy.da.UpdateCursor(points, ["Base", "Top",rastername, fieldname]) as cursor:
 for row in cursor:
 if (row[3] >= row[0] and row[3] <= row[1]):
 row[4] = 1
 if not (row[3] >= row[0] and row[3] <= row[1]):
 row[4] = 0
 cursor.updateRow(row)
 print "Processing perf flags for " + rastername

• Vince: Python Array Use 101: indexes start at zero, and you only provide four field names, so row[4] is out of range.

Answer 1

Your update cursor has four values in its row: ["Base", "Top",rastername, fieldname] corresponding to row[0],row[1],row[2],row[3] respectively. row[4] is out of range because it is the fifth of four items.

• phead: Thanks for the help.I'm not sure how I missed that, as I accounted for row[0].. I adjusted the script and it ran as expected. Thanks again for looking it over!