How to Identify Consecutive Number Groups in a Python List?

Identifying Consecutive Number Groups in a List

In Python, identifying groups of consecutive numbers in a list can be achieved through various methods. Here's a discussion of the available options:

1. Using GroupBy Recipe from Python Docs:

Python provides an elegant recipe for this task. GroupBy iterates over enumerated list items, grouping consecutive numbers:

from operator import itemgetter
from itertools import groupby

data = [2, 3, 4, 5, 12, 13, 14, 15, 16, 17]
for k, g in groupby(enumerate(data), lambda (i,x):i-x):
    print(map(itemgetter(1), g))

This will output groups of consecutive numbers:

[2, 3, 4, 5]
[12, 13, 14, 15, 16, 17]

2. Modifying the GroupBy Output:

To obtain the requested tuple format, you can modify the output as follows:

ranges = []
for k, g in groupby(enumerate(data), lambda (i,x):i-x):
    group = map(itemgetter(1), g)
    ranges.append((group[0], group[-1]))

This will output:

[(2, 5), (12, 17)]

3. Custom Implementation:

You can also implement your own custom solution:

ranges = []
for key, group in groupby(enumerate(data), lambda (index, item): index - item):
    group = map(itemgetter(1), group)
    if len(group) > 1:
        ranges.append(xrange(group[0], group[-1]))
    else:
        ranges.append(group[0])

Handling Individual Numbers:

To return individual numbers as individual elements, simply modify the custom implementation code as follows:

...
    if len(group) > 1:
        ranges.append(xrange(group[0], group[-1]+1))
    else:
        ranges.append(group[0])

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