topic Re: Make feature layer & Select by attribute in Geoprocessing Questions

Make feature layer & Select by attribute

Andreas_ForøTollefsen — Mon, 28 Jun 2010 10:14:57 GMT

Hi all.

I need to loop and split a polygon shapefile using a list of values that i want to incorporate into my query.
However, I cannot get the query to work properly.
How can i use variable x in the query?

Thanks.

# Import system modules
import sys, string, os, arcgisscripting

# Create the Geoprocessor object
gp = arcgisscripting.create()
gp.overwriteoutput = 1

# Load required toolboxes...
gp.AddToolbox("C:/Program Files/ArcGIS/ArcToolbox/Toolboxes/Data Management Tools.tbx")

# Set workspace
gp.workspace = "C:\\geodata\\PRIO_GRID\\Data_Sources\\cShapes0.24\\"

# Create list
yearlist = list(range(1946, 2009))

# Process: Select Layer By Attribute...
for x in yearlist:
    gp.MakeFeatureLayer("cshapes.shp","lyr")
    gp.SelectLayerByAttribute("lyr", "new_selection", "\"gwsyear\" <= x AND \"gweyear\" >= x")
    gp.CopyFeatures("lyr", "cshapes"+x)

Re: Make feature layer & Select by attribute

RDHarles — Mon, 28 Jun 2010 15:31:22 GMT

How/Where are you setting variables gwsyear & gweyear?
Is it possible you are setting them as a string instead of a number?

Re: Make feature layer & Select by attribute

ChrisMathers — Sat, 11 Dec 2021 09:19:39 GMT

The problem is that the geoprocessor isnt looking at that x as a variable, just a part of the query string. Build your query outside of that tool and just make the query string a variable. You dont need to escape every quote in the geoprocessing tools, its better to use string literals when making an input variable like this. You may have to convert your date into strings if they are stored as integers so that the string can concatenate.

 
Query=r'""qwsyear" <= ' + str(x) + r' AND "gweyear" >= ' + str(x) + r'"'
 
gp.SelectLayerByAttribute("lyr", "new_selection", Query)
 
 
>>> x=1957
>>> query=r'""qwsyear" <= ' + str(x) + r' AND "gweyear" >= ' + str(x) + r'"'
>>> query
'""qwsyear" <= 1957 AND "gweyear" >= 1957"'

Re: Make feature layer & Select by attribute

Andreas_ForøTollefsen — Sat, 11 Dec 2021 09:19:42 GMT

Great. That worked.

Here is my code:

# Import system modules
import sys, string, os, arcgisscripting

# Create the Geoprocessor object
gp = arcgisscripting.create(9.3)
gp.overwriteoutput = 1

# Load required toolboxes...
gp.AddToolbox("C:/Program Files/ArcGIS/ArcToolbox/Toolboxes/Data Management Tools.tbx")

# Set workspace
gp.workspace = "C:\\geodata\\PRIO_GRID\\Data_Sources\\cShapes0.24\\"

# Create list
yearlist = list(range(1946, 2009))

# Define emptygrid
emptygrid = "C:\\geodata\\PRIO_GRID\\Data_Sources\\EmptyGrid\\emptygrid230610_WGS.shp"

# Select cShapes year and copy each year to new shapefile
for x in yearlist:
    query ="GWSYEAR <= " + str(x) + " " + "AND" + " " + "GWEYEAR >= " + str(x)
    gp.MakeFeatureLayer("cshapes.shp","lyr")
    gp.SelectLayerByAttribute("lyr", "new_selection", query)
    gp.CopyFeatures("lyr", "cshapes"+str(x))
    
del yearlist, query, x, emptygrid
print "completed"