统计数组元素出现的个数

javascript

var user_list = ['zhangsan','zhangsan','lisi','wangwu','hmm','hmm','hmm']

var transportation  = user_list.reduce(function(obj, item) {
  if (!obj[item]) {
    obj[item] = 0
  }
  obj[item]++

  return obj
}, {})

transportation

{ zhangsan: 2, lisi: 1, wangwu: 1, hmm: 3 }

python

from collections import Counter
arr=[1,2,5,1,1,5,6,3,3,2,2,4,8]

def counter(arr):

    return Counter(arr)

print(counter(arr))

得到结果:

Counter({1: 3, 2: 3, 5: 2, 3: 2, 6: 1, 4: 1, 8: 1})