[Python(파이썬)] 리스트의 특정 원소 개수 구하기, Counter

리스트의 특정 원소 개수 구하기

 

• count() - 리스트의 특정 원소 개수 구하는 함수

>>> test = [1, 3, 5, 2, 1, 3, 6, 8]
>>> test.count(1)
2
>>> test.count(8)
1

 

>>> test = ['abc', 'apple', 'abaegd', 'abcdeaa', 'cba']
>>> temp = []
>>> for i in test:
	temp.append(i.count('a'))

	
>>> temp
[1, 1, 2, 3, 1]

 

 

 

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리스트안 전체 요소의 개수를 각 각 구하기

from collections import Counter

 

• Counter(리스트명)

>>> from collections import Counter
>>> test = [1, 2, 3, 5, 4, 3, 2, 1, 1, 8]

>>> a = Counter(test)

>>> type(a)
<class 'collections.Counter'>

>>> a
Counter({1: 3, 2: 2, 3: 2, 5: 1, 4: 1, 8: 1})

 

 

• Counter(리스트명).most_common() - 튜플 형태로 값을 반환

>>> from collections import Counter
>>> test = [1, 2, 3, 5, 4, 3, 2, 1, 1, 8]

>>> b = Counter(test).most_common()

>>> type(b)
<class 'list'>

>>> b
[(1, 3), (2, 2), (3, 2), (5, 1), (4, 1), (8, 1)]

 

 

# set
>>> test = {1, 3, 2, 5, 1}
>>> Counter(test)
Counter({1: 1, 2: 1, 3: 1, 5: 1})

# 튜플
>>> test = (1,3,2,5,1)
>>> Counter(test)
Counter({1: 2, 3: 1, 2: 1, 5: 1})

# 문자열 1
>>> test = ['a','b','c','d','e']
>>> Counter(test)
Counter({'a': 1, 'b': 1, 'c': 1, 'd': 1, 'e': 1})

# 문자열 2
>>> test = ['ab', 'a', 'c', 'abc']
>>> Counter(test)
Counter({'ab': 1, 'a': 1, 'c': 1, 'abc': 1})