Append values to a set in Python

Question

I have a set like this:

keep = set(generic_drugs_mapping[drug] for drug in drug_input) 

How do I add values [0,1,2,3,4,5,6,7,8,9,10] into this set?

Answer 1

keep.update(yoursequenceofvalues) 

e.g, keep.update(xrange(11)) for your specific example. Or, if you have to produce the values in a loop for some other reason,

for ...whatever...:   onemorevalue = ...whatever...   keep.add(onemorevalue) 

But, of course, doing it in bulk with a single .update call is faster and handier, when otherwise feasible.

Answer 2

Define set

a = set() 

Use add to append single values

a.add(1) a.add(2) 

Use update to add elements from tuples, sets, lists or frozen-sets

a.update([3,4])  >> print(a) {1, 2, 3, 4} 

If you want to add a tuple or frozen-set itself, use add

a.add((5, 6))  >> print(a) {1, 2, 3, 4, (5, 6)} 

Note: Since set elements must be hashable, and lists are considered mutable, you cannot add a list to a set. You also cannot add other sets to a set. You can however, add the elements from lists and sets as demonstrated with the ".update" method.