Here's how I do it. I have a function as this something I find myself doing a lot! This function works in 10.0 and 10.1. It reads a table, not a text file. (If you add a field name to the top of your text file, and name the file with a .csv or .txt file extension you can read it directly as a table in ArcGIS.)
def ListUnique(inTable, Field):
"""Create a list of unique values from a table/tableview.
arguments
inTable Table or table view
Field Field name
"""
try:
try:
# this will only work for 10.1
import arcpy.da
lstValues = [r[0] for r in
arcpy.da.SearchCursor(inTable, Field)]
except ImportError:
# 10.0 version
try:
Rows = arcpy.SearchCursor(inTable, "", "", Field, Field)
Row = Rows.next()
lstValues = []
while Row:
lstValues.append(Row.getValue(Field))
Row = Rows.next()
except:
raise
finally:
del Row, Rows
# unique-ize and sort the list
lstValues = sorted(set(lstValues))
return lstValues
except Exception as msg:
raise Exception("ListUnique failed\n" + str(msg))
Once you have the list of values, you can make this into a SQL expression from a list like this:
numlist = ",".join(str(L))
strlist = ",".join(["'{}'".format(vv) for vv in L]) # need quotes for string values
where = '"{}" IN ({})'.format(field, numlist) # "FIELD" IN (1,2,3)
James wanted me to use the FIELD = 1 OR FIELD = 2 syntax, so here's a way to do that (this replaces line 03 above):
where = " OR ".join(['"{}" = {}'.format(field, k) for k in strlist])
