标签：下划线 第一个 pen find 例题 counter iterator 插入 UNC
目录
import re从字符串里找特定的字符串
^匹配开头
s = 'abdhgtsab'
print(re.findall('^abd',s))
# ['abd'] 开头有就输出abd，没有就回返回[]$ 匹配结尾
s = 'abdhgtsab'
print(re.findall('ab$',s))
# ['ab'] 结尾有就返回ab，没有就返回[][] 匹配[]内的字符
s = 'acefghjkacefsdfsdf'
print(re.findall('[acef]', s)) # 只要[]内的单个字符
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['a', 'c', 'e', 'f', 'a', 'c', 'e', 'f', 'f', 'f']^[]对[]里面的元素取反,取出除了[]内的元素外的每个字符
s = 'acefghjkacefsdfsdf'
print(re.findall('[^acef]', s))
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['g', 'h', 'j', 'k', 's', 'd', 's', 'd'].任意字符（除了\n）
s = 'acefghjkacefsdfsdf'
print(re.findall('a..', s))
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['aba', 'ada']*前面的字符0-无穷个s = 'abaacaaaaa'
print(re.findall('a*', s))
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['a', '', 'aa', '', 'aaaaa', '']+前面的字符1-无穷个s = 'abaacaaaaa'
print(re.findall('a+', s))
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['a', 'aa', 'aaaaa']?前面的字符0-1个s = 'abaacaaaaa'
print(re.findall('a?', s))
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['a', '', 'a', 'a', '', 'a', 'a', 'a', 'a', 'a', '']{m}前面的字符m个s = 'abaacaaaaa'
print(re.findall('a{5}', s))
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['aaaaa']{m,n}前面的字符m-n个s = 'abaacaaaaa'
print(re.findall('a{2,5}', s))
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['aa', 'aaaaa']\d数字s = 's 1 s+\n=$\t2_s 3'
print(re.findall('\d', s)
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['1', '2', '3']\D非数字s = 's 1 s+\n=$\t2_s 3'
print(re.findall('\D', s)
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['s', ' ', ' ', ' ', ' ', ' ', 's', '+', '\n', '=', '$', '\t', '_', 's', ' ', ' ']\w数字/字母/下划线s = 's 1 s+\n=$\t2_s 3'
print(re.findall('\w', s))
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['s', '1', 's', '2', '_', 's', '3']\W非数字/字母/下划线s = 's 1 s+\n=$\t2_s 3'
print(re.findall('\W', s))
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[' ', ' ', ' ', ' ', ' ', '+', '\n', '=', '$', '\t', ' ', ' ']\s空格/\t/\ns = 's 1 s+\n=$\t2_s 3'
print(re.findall('\s', s))
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[' ', ' ', ' ', ' ', ' ', '\n', '\t', ' ', ' ']\S非空格/\t/\ns = 's 1 s+\n=$\t2_s 3'
print(re.findall('\S', s))
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['s', '1', 's', '+', '=', '$', '2', '_', 's', '3']\取消意义s = 'aba\d'
print(re.findall(r'a\\d', s))
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['a\\d'].*贪婪模式(最大化),找到继续找,让结果最大化s = 'abbbcabc'
print(re.findall('a.*c', s))
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['abbbcabc'].*?非贪婪模式(最小化),找到就马上停止s = 'abbbcabc'
print(re.findall('a.*?c', s))
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['abbbc', 'abc']()只要括号内的s = 'abacad'
print(re.findall('a(.)', s))
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['b', 'c', 'd']A|B A和B都要s = 'abacad'
print(re.findall('a|b', s))
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['a', 'b', 'a', 'a']re.mathch(): 从开头搜索,搜索到了就有,没搜索到就是none
s = 'abc123\ndef456'
res = re.match('\d+', s) #从开头搜索数字,搜索到了就有,没搜索到就是none
print(res)
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None
s = '123abc123\ndef456'
res = re.match('\d+', s)
print(res) #返回的是一个对象
print(res.group()) #对象必须用group()返回
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<re.Match object; span=(0, 3), match='123'>re.search(): 搜索第一个匹配结果,找到了就不找了
s = '123abc123\ndef456'
res = re.search('\d+', s)
print(res)
print(res.group())
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123re.split(): 按照匹配规则切割
s1 = 'abc324asdfk234lkjsf324lkj'
print(re.split('\d+', s1))
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['abc', 'asdfk', 'lkjsf', 'lkj']re.sub(): 按照匹配规则替换(重点)
s1 = 'abc324asdfk234lkjsf324lkj'
print(re.sub('\d+', '***', s1))
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abc***asdfk***lkjsf***lkjre.subn(): 按照匹配规则替换,并计数
s1 = 'abc324asdfk234lkjsf324lkj'
print(re.subn('\d+', '***', s1))
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('abc***asdfk***lkjsf***lkj', 3)例题：
? 1.对于字符串Life234234is beautiful234because234of persistence
? 2.请使用re模块 一行代码 还原这句话为Life is beautiful because of persistence
import re
s = 'Life234234is beautiful234because234of persistence'
# 结果为：Life is beautiful because of persistence解答：
print(" ".join(re.sub('[0-9]', " ", s).split()))from typing import xxx提供生成器类型（cenerator），可迭代类型（iterable），迭代器类型（iterator）三种数据类型，限制函数
from typing import Generator,Iterable,Iterator
# 参数的数据类型 返回值
def func(i: int, f: float, b: bool, lt: list, tup: tuple, dic: dict,g:Generator) -> tuple:
lis = [i, f, b, lt, tup, dic]
return tuple(lis)
# i, f, b, lt, tup, dic = func(1,2,3,4,5,6) # 不错误,只是不规范
def ger():
yield
res = func(1, 2, True, [1, 2], (1, 2), {'a': 1},ger())
print(res)
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(1, 2, True, [1, 2], (1, 2), {'a': 1})from collections import xxx用于复杂的数据类型
from collections import namedtuple
point = namedtuple('point',['x','y'])
p = point(1,2)
print(p.x)
print(p.y)
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1
2from collections import defaultdict
# dic = {'a':1}
# print(dic['b'])
dic = defaultdict(lambda :'nan') # dic = {} # 如果找不到赋了一个默认值
dic['a'] = 1
print(dic['a'])
print(dic['c']) #找不到关键字c给c赋了一个默认值nan
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1
nandeque
使用list存储数据时，按索引访问元素很快，但是插入和删除元素就很慢了，因为list是线性存储，数据量大的时候，插入和删除效率很低。
deque是为了高效实现插入和删除操作的双向列表，适合用于队列和栈：
# lis = [1,2,3] # 线性表
# lis.append(4) #在后面追加4
# print(lis)
from collections import deque # 链表
de = deque([1,2,3])
de.append(4) #在最后面追加4
print(de)
de.appendleft(0) #在最前面追加0
print(de) # 默认删除左边的
de.popleft()
print(de)
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deque([1, 2, 3, 4])'''比较麻烦的方法'''
s= 'programming'
# dic = {}
# for i in s:
# if i in dic:
# dic[i]+=1
# else:
# dic[i] =1
# print(dic)
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{'p': 1, 'r': 2, 'o': 1, 'g': 2, 'a': 1, 'm': 2, 'i': 1, 'n': 1}# 新方法
from collections import Counter
s= 'programming'
c = Counter() # 字典
for i in s:
c[i] +=1 #在内部自己进行了一个判断
print(c)
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Counter({'r': 2, 'g': 2, 'm': 2, 'p': 1, 'o': 1, 'a': 1, 'i': 1, 'n': 1})re 模块、typing 模块、collections 模块
标签：下划线 第一个 pen find 例题 counter iterator 插入 UNC
原文地址：https://www.cnblogs.com/zhuangyl23/p/11403001.html
