python高级技巧（二）

字符串处理技巧

拆分字符串

# coding=utf-8import res1 = "a b c d e f g h i j k"res1 = s1.split()print(res1)s2 = 'a;b|c,d-e|f\tg;h,i&j k'res2 = re.split('[-,;|\t& ]', s2)print(res2)

endswith() startwith()

# coding=utf-8import ospath = './data'files = os.listdir(path)py = filter(lambda s: s.endswith('.py'), files)sh_c = filter(lambda x: x.endswith(('.sh', '.c')), files)print(list(sh_c))

调整字符串顺序

2017-10-28 ==》10/28/2017

import refilename = './data/log'with open(filename) as f:    for line in f:        #rline = re.sub('(\d{4})-(\d{2})-(\d{2})', r'\2/\3/\1', line[:100])        rline = re.sub('(?P<year>\d{4})-(?P<mouth>\d{2})-(?P<day>\d{2})',                       r'\g<mouth>/\g<day>/\g<year>', line[:100])        print(rline)

拼接字符串

# str+str 加号就不多说了，元素多了，他就需要不停的创建释放对象，开销太大# [x for x in something] 叫做“列表解析”，内存开销很大# (x for x in something) 叫做“生成器”  ，内存占用小，对于大文件很有效aa = ['h', 'el', 'lo']resaa = ''.join(aa)bb = ['q', 1, '2', 'qwe']resbb = ''.join(str(x) for x in bb)print(resaa, resbb)

对齐

person = {    'name': 'xiaoming',    'age': '23',    'sex': 'male',    'good_friends': 'a,b,v',    'hobby': 'socker'}w = max(map(len, person.keys()))# ljust rjust center 左右上对齐for k, v in person.items():    print(k.ljust(w), ':', v)# <   >   ^   左右上对齐# for k, v in person.items():#     print(format(k, '<3'), v)

去掉不要的字符串

import res = '-----hello-----world-----'print(s.lstrip('='))print(s.rstrip('='))print(s.strip('='))s = '123-qwe'print(s[:3]+s[4:])print(s.replace('-', ''))s2 = 'a;b|c,d-e|f\tg;h,i&j k's2 = re.sub('[-,;|\t& ]', '', s2)print(s2)