Use sets and Tuples in Python

Use sets and Tuples in Python

1. Create sets using the syntax test_set = {item1, item2, item3} to store numbers or sets of words.

Sets are encapsulated within curly brackets { }. For example: set1 = {3,22,1,56} set2 = {'hello', 'Sara', 11, 'Matt', 23.89} Sets can only contain unique values. If you try creating a set with duplicate values, Python will automatically remove such values. For example, typing set5 at the command line for the following set will return {1, 2, "one", 3}: set5= {1,2,"one", 3, 1, "one"}

2. Use the len() function to obtain the length and determine the number of items in a set.

For example, the len() function below would return 3, since there are three values in the set: sample_set = {"one", "two", "three"} >>> len(sample_set)

3. Use the max(), min(), and sum() built-in functions to obtain the maximum, minimum, and sum of the values within the set.

For example, in the following sample set, max(sample_set) would return 3, min(sample_set) would return 1, and sum(sample_set) would return 6: >>> sample_set = {1,2,3} >>> max(sample_set) >>> min(sample_set) >>> sum(sample_set)

4. Use the add() and remove() methods to add or remove values from a set.

For example, with the following sample set, sample_set.add(5) would result in sample_set{1,2,3,4,5}, and sample_set.remove(4) would result in sample_set{1,2,3}: >>> sample_set = {1,2,3,4} If you try to remove an element that doesn’t exist in the set, the remove() method will throw a KeyError exception. You can also use discard() method to remove the element from the set, but this method will ignore any errors. For instance, sample_set.discard(6) used with the above sample set would not give a result or return an error.

5. Loop through sets using the for method to iterate over the elements in a set and obtain the values in sequence or to obtain a specific value based on index.

For example: >>> sample_set = {1,2,3} >>>  >>> for i in sample_set: ...     print(i) ...  1 2 3

6. Use issubset() and issuperset() to find out whether two sets contain any common values.

For example, set A is a subset of B, and both sets contain the common values 1,2, and 3: A = {1,2,3,4,5,6,7,8,9,10} B = {1,2,3} You could use issubset() to find out whether all values of set B are values in Set A, and issuperset() to find out whether any of the elements in Set A are also in Set B: >>> >>> A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} >>> B = {1, 2, 3} >>> >>> A.issubset(B) False >>> >>> B.issubset(A) True >>> >>> B.issuperset(A) False >>> >>> A.issuperset(B) True >>>

7. Use relational operators like = , > , and < to compare sets and find out whether a set is a subset or superset of another set.

For example: >>> >>> A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} >>> B = {1, 2, 3} >>> >>> B >> >>> A >> >>> B > A False >>> >>> A > B True >>> The == and != operators can also be used to test if two sets contain the same elements. For example: >>> >>> s1 = {1,3,2} >>> s2 = {1,2,3} >>> >>> s1 == s2 True >>> s1 != s2 False >>> >>> B >= {1,2,3} True >>> >>> A >>

8. Use the ∪ union method to combine two sets.

Symbolically, we would write a union between A and B as A ∪ B. For example: A = {10, 20, 30, 40} B = {1000, 2000} A ∪ B => {10, 20, 30, 40, 1000, 2000} You can also use the union() method or | operator to create unions and combine sets. For example: >>> >>> n1 = {2, 3, 4, 10} >>> n2 = {10, 2, 100, 2000} >>> >>> n3 = n1.union(n2) >>> n3 {2, 3, 4, 100, 10, 2000} >>> >>> n4 = n1 | n2 >>> n4 {2, 3, 4, 100, 10, 2000} >>>

9. Separate list values with a comma and enclose them in parentheses to create tuples with values that don't change.

In the example below, t is a tuple created with alpha, delta, and omega as its values. >>> >>> t = ("alpha", "delta", "omega") >>> >>> t ('alpha', 'delta', 'omega') >>> >>> type(t) >>>