用于计数
from collections import Counter a =list(range(10)) b = Counter(a) print(b) a.append(1) b = Counter(a) print(b) print(b[1])
结果:
Counter({0: 1, 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1})
Counter({1: 2, 0: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1})
2