高效python代码持续积累

有时候经常容易忘一些快速的数据实现结构，从此做一些记录。

1. 根据二维数组首元素排序，如下：

data = [[2,3],[5,4],[9,6],[4,7],[8,1]]
data.sort(key=lambda x:x[0])
print(data)
[[2, 3], [4, 7], [5, 4], [8, 1], [9, 6]]

 2.快速去重

def dedupe(items, key=None):
 """
 items: 哈希或者不可哈希的序列
 key: 若items为不可哈希的序列(dict等)则需要指定一个函数
 """
 seen = set()
 for item in items:
     val = item if key is None else key(item)
     if val not in seen:
         yield item
         seen.add(val)

nums = [1,2,32,2,2,4,3,2,3,42]
print(list(dedupe(nums)))
# [1, 2, 32, 4, 3, 42]

students = [
 {"name": "Stanley", "score": 88},
 {"name": "Lily", "score": 92},
 {"name": "Bob", "score": 91},
 {"name": "Well", "score": 80},
 {"name": "Bob", "score": 90},
 {"name": "Peter", "score": 80}
]
deduped_students = list(dedupe(students, key=lambda s: s['name']))
print(deduped_students)
"""
[{'name': 'Stanley', 'score': 88},
{'name': 'Lily', 'score': 92},
{'name': 'Bob', 'score': 91},
{'name': 'Well', 'score': 80},
{'name': 'Peter', 'score': 80}]   # 删除了相同姓名的元素
"""
# 删除姓名和分数都相同的元素
deduped_students = list(dedupe(students, key=lambda s: (s['name'], s['score'])))