Python Sets
Creating and Accessing:
mySet = {"myVal1", "myVal2", "myVal3"} # Create a set with 3 values
print( "myVal1" in mySet ) # Display True if Set contains a specifed value
- A set is like a list of distinct items, it can only store one of each item, it will ignore addition of an item that it contains
- Sets are useful for defining groups and comparing their relationships
- A set can be of different types, including multiple types in the same set
- You can also create a set from a list with set(myList)
Add Items:
mySet.add("myAddedVal") # Add one
mySet.update(["val5", "val6"]) # Add multiple
Remove Items:
mySet.remove("myVal1") # Remove one (error if not there)
mySet.discard("myVal2") # Remove one (no error if not there)
mySet.clear() # Remove all values
Operations:
mySet1 & mySet2 # Intersection (values in common)
mySet1.intersection(mySet2) # Alternative way to get intersection
mySet1.union(mySet2) # All values among both
mySet1.issubset(mySet2) # True if set2 contains all values of set1
mySet1.issuperset(mySet2) # True if all values of set2 are contained in set1
mySet1.difference(mySet2) # Returns set with items unique to set1 (in set1 but not set2)
mySet1.symmetric_difference(mySet2) # True if in one set or other but not at intersection
- These are ways that relationships between groups are explored
Challenge
Create a set that contains teh numbers from 10 to 20, and another set with the prime numbers from 2 to 19. Display the numbers that are in common between the two sets, and then display the numbers that are unique to the second set.
Completed