# The Python code implements finding odd even exceptions in the list

• 2021-12-12 09:16:17
• OfStack

Directory 1. find_parity_outliers 2.class collections.Counter([iterable-or-mapping])

## 1.find_parity_outliers

``````
from collections import Counter

def find_parity_outliers(nums):
return [
x for x in nums
if x % 2 != Counter([n % 2 for n in nums]).most_common()[0][0]
]

# EXAMPLES
find_parity_outliers([1, 2, 3, 4, 6]) # [1, 3]

``````

`find_parity_outliers` The function receives a list and returns parity exceptions in the list. Parity exception items refer to items with different parity properties from most items in the list. The function uses a list derivation to check whether every 1 item in the input list is an odd-even exception. `Counter` Use list derivation and remainder operation (% 2) to extract the parity properties of each item in its input list one by one. Use `collections.Counter.most_common()` To get the most common parity in the list.

## 2.class collections.Counter([iterable-or-mapping])

Counter is a subclass of dict that counts hashable objects. It is a collection, the elements are stored like dictionary keys (key) 1, and their counts are stored as values. The count can be any integer value, including 0 and negative numbers. `most_common([n])` Yes `Counter` Provides 1 method that

Returns a list of the most common elements of n and the number of occurrences, sorted from most common to least common. If n is omitted or None, most_common () returns all elements in the counter. Elements with equal count values are sorted in the order in which they first appear.

``````
>>> from collections import Counter
``````