Problem with expression using select by attributes

Discussion created by mstrand on Jul 26, 2011
Latest reply on Jul 26, 2011 by stacyrendall
I have been working on a code to automate the process of finding the relative probability of failure for all of the water mains in a city and am having a problem using select by attributes. The code gives me an error saying "invalid expression". I have narrowed it down to this line:
Select(AC_Fail,"NEW_SELECTION",ACFDia + ' = ' + str(x))

I know this is the line giving me problems because I commented it out and the rest of the script ran fine. The line before is written the exact same way, but it works. (Weird)

Below, I have included everything in my script just to past the point where I am getting the error.
import arcpy, sys
arcpy.env.workspace = "C:\Data\ArcGIS\Default.gdb"

#Define input and output variables
WaterPipes = sys.argv[1]
WPID = sys.argv[2]
WDia = sys.argv[3]
YearInst = sys.argv[4]
AC_Fail = sys.argv[5]
ACFDia = sys.argv[6]
SoftPunky = sys.argv[7]
PipeTests = sys.argv[8]
FailCategory = sys.argv[9]
ServiceFail = sys.argv[10]
OEM = sys.argv[11]
Probability = sys.argv[12]

#Define variables to make code readable
Select = arcpy.SelectLayerByAttribute_management
SpatialJoin = arcpy.SpatialJoin_analysis
Merge = arcpy.Merge_management
AddField = arcpy.AddField_management
MakeLayer = arcpy.MakeFeatureLayer_management
Calculate = arcpy.CalculateField_management
JoinField = arcpy.JoinField_management
Delete = arcpy.Delete_management

#Clear any selections on all input layers
Select(WaterPipes, "CLEAR_SELECTION")
Select(SoftPunky, "CLEAR_SELECTION")
Select(PipeTests, "CLEAR_SELECTION")
Select(ServiceFail, "CLEAR_SELECTION")

#Define pipe sizes
dia = []
rows = arcpy.SearchCursor(WaterPipes,"","",WDia,"")

for row in rows:
    if getattr(row, WDia) not in dia:
        dia.append(int(getattr(row, WDia)))

#For each pipe size, select all pipes of that size on the water pipes layer and the AC failure layer
#Join the two layers together to create a layer that counts the number of
#failures on the same diameter of pipe within 100 feet.
layers = []
for x in dia:
    Select(WaterPipes,"NEW_SELECTION",WDia + ' = ' + str(x))
    Select(AC_Fail,"NEW_SELECTION",ACFDia + ' = ' + str(x))
    SpatialJoin(WaterPipes,AC_Fail,'Fail100' + str(x),"JOIN_ONE_TO_ONE","KEEP_ALL","","INTERSECT",100,"Dist")
    layers.append('Fail100' + str(x))

#Merge all of the different pipe size layers together into one layer.

Why isn't this working?

Any help is much appreciated. If I haven't included enough information, let me know.