Defining fields to keep and deleting all other fields in feature class using ArcPy?

Question

I am trying to write a script to read a feature class, list all fields and keep only specic ones. I.e. drop all remaining columns.

I guess that pseudo code should be:

1. allFields = create list of all fields
2. fieldToKeep = define list of fields to keep (manually)
3. fieldsToDrop = different items between list 1 and list2 = to remove
4. execute arcpy.DeleteField_management(inFC, fieldsToDrop) to remove uncecessary fields

Should be pretty simple, but I cannot figure out steps and conditioning in correct order?

# Input point data
inFC= "inFC"

# CHeck if field exist,if yes, delete the field
allFields = arcpy.ListFields(inFC)

fieldsToKeep = ["OBJECTID", "Shape", "Country", "manualChange"]
fieldsToDrop = []  # define new empty list

for field in allFields:   # how to difference two lists?
    if not field in fieldsToKeep:
        fields.remove(field)

# Execute DeleteField
arcpy.DeleteField_management(inFC, fieldsToDrop)

Answer 1

You can use python sets to calculate fieldsToDrop and loop over it to remove the desired fields like so:

# Input point data
inFC= "inFC"

# CHeck if field exist,if yes, delete the field
allFields = [f.name for f in arcpy.ListFields(inFC)]

fieldsToKeep = ["OBJECTID", "Shape", "Country", "manualChange"]
fieldsToDrop = list(set(allFields) - set(fieldsToKeep))

# Execute DeleteField
arcpy.DeleteField_management(inFC, fieldsToDrop)

See also Get difference between two lists