What is enumerate()?

• A function for obtaining the indices and list values together when a list is present

1. Configuration

1-1. Syntax

• enumerate(iterable, start=0)

• Additional explanation: Takes an iterable data type (list, set, tuple, dictionary, string) as input, bundles the index values and elements into tuples, and returns an enumerate object

1-2. Parameters

• iterable: An iterable data type (list, set, tuple, dictionary, string)
• start=0: The starting value for the index ex)

list(enumerate(seasons, start=1))
[(1, 'Spring'), (2, 'Summer'), (3, 'Fall'), (4, 'Winter')]

2. Usage

• It is mainly used in for loops
• When you want to obtain the index and element simultaneously

>>> for entry in enumerate(['A', 'B', 'C']):
...     print(entry)
...
(0, 'A')
(1, 'B')
(2, 'C')

tip) Advanced application (two-dimensional matrix)

>>> matrix = [['A', 'B', 'C'], ['D', 'E', 'F'], ['G', 'H', 'I']]

# 일반 
>>> for r in range(len(matrix)):
...     for c in range(len(matrix[r])):
...             print(r, c, matrix[r][c])
...
0 0 A
0 1 B
0 2 C
1 0 D
1 1 E
1 2 F
2 0 G
2 1 H
2 2 I

You can determine the coordinates of a two-dimensional matrix all at once with more readable code.

# enumerate 응용
>>> for r, row in enumerate(matrix):
...     for c, letter in enumerate(row):
...             print(r, c, letter)
...
0 0 A
0 1 B
0 2 C
1 0 D
1 1 E
1 2 F
2 0 G
2 1 H
2 2 I

3. Summary

• Use enumerate when you want to obtain the indices and elements simultaneously through a for loop.

References 1.https://www.daleseo.com/python-enumerate/ 2.https://wikidocs.net/20792