5. Enumerate

See: Python enumerate: https://www.w3schools.com/python/ref_func_enumerate.asp

The enumerate() function takes a collection (e.g. a list) and returns it as an enumerate object which is like a dictionary.

The enumerate() function adds a counter as the key of the enumerate object.

Syntax:

enumerate(iterable, start)

Parameters:

• iterable – An iterable object, such as a list, tuple or string.

• integer – The start number of the enumerate object. Default 0

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The enumerate object can be converted to a dictionary using the dict() function.

fruit = ['apple', 'banana', 'cherry']
fruit_enum = enumerate(fruit)

print(dict(fruit_enum))

The print output is: {0: ‘apple’, 1: ‘banana’, 2: ‘cherry’}

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The enumerate object can be looped through using a for-loop.

fruit = ['apple', 'banana', 'cherry']
fruit_enum = enumerate(fruit)


for num, element in fruit_enum:
    print(num, element, end="; ")

The print output is: 0 apple; 1 banana; 2 cherry

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The keys of a dictionary can be enumerated.

shapes = {'a': 'triangle', 'b': 'square', 'c': 'pentagon'}

for num, key in enumerate(shapes):
    print(num, key, end="; ")

The print output is: 0 a; 1 b; 2 c;

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The values of a dictionary can be enumerated.

shapes = {'a': 'triangle', 'b': 'square', 'c': 'pentagon'}

for num, value in enumerate(shapes.values()):
    print(num, value, end="; ")

The print output is: 0 triangle; 1 square; 2 pentagon;

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The items of a dictionary can be enumerated.

Each item is a tuple of (key, value) from the shapes dictioary.

shapes = {'a': 'triangle', 'b': 'square', 'c': 'pentagon'}

for num, (key, value) in enumerate(shapes.items()):
    print(num, key, value, end="; ")

The print output is: 0 a triangle; 1 b square; 2 c pentagon;