Necessity is the mother of invention and as of late, this means I have learned to use Python with ArcGIS. Early on, an issue I ran across was needing a list of all unique values in a field to be used in further analysis. Unfortunately there is not a pre-built method for this. Still, it did not take long to figure out the following function to accomplish this.
# Return list all permutations of field in input feature class or table
def getValueList (inputTable, field):
valueList = [] # array to hold list of values collected
valueSet = set() # set to hold values to test against to get list
rows = arcpy.SearchCursor(inputTable) # create search cursor
# iterate through table and collect unique values
for row in rows:
value = row.getValue(field)
# add value if not already added and not current year
if value not in valueSet:
valueList.append(value)
# add value to valueset for checking against in next iteration
valueSet.add(value)
# return value list
valueList.sort()
return valueList
Hopefully if you have run across this problem, you find this useful. If you know of a better method, please comment and let me know!
The World Bank – Mapping for Results web mapping application