Python 常用编程知识---排序操作

排序操作

打算把自己平时经常用到，但是又经常记不准的python语法整理一下，这是第一篇，希望可以帮到你

Outline

字典排序；（按key，按value排序）

list单元素排序（升序，降序）

list多元素

import numpy as np

n_num = 5

字典排序；（按key，按value排序）

# 字典排序
val = np.random.randint(low=0, high=100,size=n_num, dtype=np.int32)
key_list = ['a', 'b', 'c', 'd', 'e']
my_dict = {}
for i in range(n_num):
my_dict[key_list[i]] = val[i]
print('Initial dict val')
for key in my_dict.keys():
print('Key = %s, \t value = %d' % (key, my_dict[key]) )

Initial dict val
Key = a,     value = 8
Key = e,     value = 68
Key = b,     value = 40
Key = c,     value = 19
Key = d,     value = 0

# 字典按 key 排序
sort_key = sorted(my_dict.items(), key = lambda x:x[0])
print('Sorted by key')
for ele in sort_key:
print(ele)

Sorted by key
('a', 8)
('b', 40)
('c', 19)
('d', 0)
('e', 68)

# 字典按 value 排序
sort_val = sorted(my_dict.items(), key = lambda x:x[1])
print('Sorted by value')
for ele in sort_val:
print(ele)

Sorted by value
('d', 0)
('a', 8)
('c', 19)
('b', 40)
('e', 68)

list单元素排序（升序，降序)

val = np.random.randint(low=0, high=100,size=n_num, dtype=np.int32)
print('Initial value')
print(val)

Initial value
[63 98 18 57 64]

# 升序 Ascending 默认
ascending_sorted = sorted(val)
print(ascending_sorted)

[18, 57, 63, 64, 98]

# 降序 Descending
descending_sorted = sorted(val, reverse=True)
print(descending_sorted)

[98, 64, 63, 57, 18]

list多元素

val1 = np.random.randint(low=0, high=100,size=n_num, dtype=np.int32)
val2 = np.random.randint(low=0, high=100,size=n_num, dtype=np.int32)
val3 = [(val1[i], val2[i]) for i in range(n_num) ]
print(val3)

[(13, 70), (68, 96), (46, 35), (40, 92), (20, 17)]

# 按第一个元素排序
sorted_by1 = sorted(val3, key = lambda x:x[0])
print(sorted_by1)

[(13, 70), (20, 17), (40, 92), (46, 35), (68, 96)]

# 按第2个元素排序
sorted_by2 = sorted(val3, key = lambda x:x[1])
print(sorted_by2)

[(20, 17), (46, 35), (13, 70), (40, 92), (68, 96)]

就是这样简单，上面的三种情况几乎可以满足我们绝大多少的排序需求了 ^_^