Sets
the collection is mutable and the elements can be added and removed to the set. The set are very similar to the dictionaries, limited by curly brackets but every item is a single objet separated by a colon
Sets are iterable although the order is arbitrary. You can mis letter and numbers.
Example:
set = {"apple", "pineapple", "grapes"}
print(set)
Output:
{'pineapple', 'apple', 'grapes'}
Note: Sets are unordered, so you cannot be sure in which order the items will appear.
Set Items
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Set items are unordered, unchangeable, and do not allow duplicate values.
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Unordered: Means that the items in a set do not have a defined order. Set items can appear in a different order every time you use them, and cannot be referred to by index or key.
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Unchangeable: Means that we cannot change the items after the set has been created.
In and not in operator
with this function you can check if a item is present or not in the code using in or in not.
Example:
#in
letters = {"s", "m", 2, "h"}
print(2 in letters)
#in not
letters = {"s", "m", 2, "h"}
print(2 not in letters)
Output - As a result will be executed answering True or False:
True
False
Duplicates no allowed
Sets cannot have two items with the same value.
Example:
letters = {"s", "m", "s", "h"}
print(letters)
Output - As a result you will see that the item that al ready exists is not present.
{'m', 's', 'h'}
Add item
Once a set is created, you cannot change its items, but you can add new items.
Example:
letters = {"s", "m", 2, "h"}
letters.add("y")
print(letters)
Output - We have this result because the order is arbitrary in the sets:
{'h', 2, 'm', 's', 'y'}
Remember, if you add a element that already exist this don't have any effect
Update
The update() method updates the current set, by adding items from another set.
If an item is present in both sets, only one appearance of this item will be present in the updated set.
Example:
letters = {"s", "m", "a", "h"}
letters.update(["r","w", "u"])
print(letters)
Output:
{"a", 's', 'r', 'w', 'u', 'm', 'h'}
Copy
letters = {"s", "m", 2, "h"}
x = letters.copy()
print(x)
Output:
{'m', 2, 's', 'h'}
Length
To determine how many items a set has, use the len() method.
Example:
letters = {"s", "m, "h"}
print(len(letters))
# Output:
3
if you repeat the same item two times the function will count it only one time
letters = {"s", "m, "s", "h"}
print(len(letters))
# Output:
3
Remove
With this function y you can delete specific item but delete a items that is not present in the set produce error.
Example:
letters = {"s", "m", 2, "h"}
letters.remove("s")
print(letters)
Output:
{2, 'h', 'm'}
Error
letters = {"s", "m", 2, "h"}
letters.remove("x")
print(letters)
Discard
The discard() method removes the specified item from the set.
This method is different from the remove() method, because the remove() method will raise an error if the specified item does not exist, and the discard() method will not.
Example - Removing existing item:
letters = set(("e", "f", "t"))
letters.discard("e")
print(letters)
Example - Removing an item that doesn’t exist:
letters = set(("e", "f", "t"))
letters.discard("h")
print(letters)
Output- In the first output you can see that the item was removed and in the second one you can see that nothing happened.
{'f', 't'}
{'t', 'e', 'f'}
Output How the letter “x” don’t was present in the set produce a error
KeyError: 'x'
Clear
method doesn’t return any value, the result is to have a empty set.
Example:
letters = set(("e", "f", "t"))
letters.clear()
print(letters)
Output:
set()
Set Items - Data Types
You can mix numbers, letter, word or even you can use true or false.
Example:
set1= {True, True, False}
set2= {"apple", "pineapple", "grapes"}
set3 = {5, 10, 15, 20, 25}
print(set1,set2,set3)
Output:
{False, True} {'pineapple', 'grapes', 'apple'} {5, 10, 15, 20, 25}
The set() Constructor
It is also possible to use the set() constructor to make a set.
Example:
letters = set(("e", "f", "t"))
print(letters)
Output- You can see that i don’t was using curly brackets.
{'f', 'e', 't'}