Tuples

The(20, 10) is a tuple. A tuple is a data structure in Python that is quite similar to a list but with some key differences. One common way to encounter a tuple is when a function returns multiple values.

For instance, consider this function that returns both the sum and the difference of two numbers:

def sum_and_difference (a, b):
    a_sum = a + b
    difference = a - b
    return a_sum, difference
    # We switched the order of return values

sum_diff = sum_and_difference(15, 5)
print(type(sum_diff))

Output
<class 'tuple'>

The function type() confirms that what's returned is a tuple.

Just like a list, we usually use a tuple to store multiple values. To create a tuple, we use parentheses to enclose the elements, separated by commas. Here's how we create and verify the type of a tuple:

a_list = [1, 'a', 10.5]
a_tuple = (1, 'a', 10.5)

print(a_tuple)
print(type(a_tuple))

Output
(1, 'a', 10.5)
<class 'tuple'>

Tuples support both positive and negative indexing, just like lists:

a_list = [1, 'a', 10.5]
a_tuple = (1, 'a', 10.5)

print(a_tuple[0])
print(a_list[0])
print(a_tuple[-1])
print(a_list[-1])

Tuples are immutable, meaning that their elements cannot be altered once they are created:

a_tuple = (1, 'a', 10.5)
a_tuple[0] = 99  # This will result in an error
print(a_tuple)

Output
TypeError: 'tuple' object does not support item assignment

If we want to return a list instead of a tuple, we need to use brackets:

def sum_and_difference (a, b):
    a_sum = a + b
    difference = a - b
    return [a_sum, difference]
    # Use brackets to return a list

sum_diff = sum_and_difference(15, 5)
print(sum_diff)
print(type(sum_diff))

Output
[20, 10]
<class 'list'>

When we work with tuples, we can assign their individual elements to separate variables in a single line of code.

We can do the same with lists — we can assign individual list elements to separate variables in a single line of code:

We can use this variable assignment technique with functions that return multiple variables.

def sum_and_difference(a, b, do_sum=True):
    a_sum = a + b
    difference = a - b
    return a_sum, difference

a_sum, a_diff = sum_and_difference(15, 5)
print(a_sum)
print(a_diff)

Output
20
10

Convert Dictionary Values to Tuples

It is very difficult to sort dictionaries. So, we can use list of tuples.

def display_table(dataset, index):
    table = freq_table(dataset, index)
    table_display = []
    for key in table:
        key_val_as_tuple = (table[key], key)
        table_display.append(key_val_as_tuple)
        
    table_sorted = sorted(table_display, reverse = True)
    for entry in table_sorted:
        print(entry[1], ':', entry[0])