python 统计数组中元素出现次数并进行排序的实例
如下所示：
lis = [12,34,456,12,34,66,223,12,5,66,12,23,66,12,66,5,456,12,66,34,5,34]
def test1():
#进行去重
c = []
for i in lis:
if i not in c:
c.append(i)
#进行统计，生成二维列表
b = []
for i in c:
num = 0
for j in range(len(lis)):
if lis[j] == i:
num += 1
a = []
a.append(i)
a.append(num)
b.append(a)
# 排序算法，按出现次数进行降序排列
for i in range(len(b)):
for j in range(i,len(b)):
if b[i][1] < b[j][1]:
temp = b[i]
b[i] = b[j]
b[j] = temp
print(b)
def test2():
# set进行去重，进行统计生成二维列表
b = []
for i in list(set(lis)):
num = 0
for j in range(len(lis)):
if lis[j] == i:
num += 1
a = []
a.append(i)
a.append(num)
b.append(a)
# 排序算法，按出现次数进行降序排列
for i in range(len(b)):
for j in range(i,len(b)):
if b[i][1] < b[j][1]:
temp = b[i]
b[i] = b[j]
b[j] = temp
print(b)
def test3():
# 统计元素出现次数，元素为key，次数为value，生成字典
a = {}
for i in lis:
if i in a:
a[i] = a[i] + 1
else:
a[i] = 1
# 使用sorted对字典进行排序
b = sorted(a.items(),key=lambda item:item[1],reverse=True)
print(b)
def test4():
from collections import Counter
import operator
#进行统计
a = dict(Counter(lis))
#进行排序
b= sorted(a.items(), key=operator.itemgetter(1),reverse=True)
print(b)
if __name__ == '__main__':
test1()
test2()
test3()
test4()
输出结果如下：
[[12, 6], [66, 5], [34, 4], [5, 3], [456, 2], [223, 1], [23, 1]] [[12, 6], [66, 5], [34, 4], [5, 3], [456, 2], [23, 1], [223, 1]] [(12, 6), (66, 5), (34, 4), (5, 3), (456, 2), (23, 1), (223, 1)] [(12, 6), (66, 5), (34, 4), (5, 3), (456, 2), (23, 1), (223, 1)]
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