Learning-python

参考 python教程-廖雪峰
To-Do * python -m
Properties pkg_resources from pkg_resources import resource_filenamedef require_path(name):return resource_filename(__name__, name) *args **kwds def study(name, age, gender='男', *args, **kwds): print('Name：%s, Age：%d, Gender：%s'%(name, age, gender)) print(args) print(kwds) ? study('snorlax', 24, '男', 175, 75, math=145, english=135)Name：snorlax, Age：24, Gender：男(175, 75){'math': 145, 'english': 135} 【Learning-python】此外， * 与 ** 还可用于列表、元组、字典的解包：
a = (1,2,3)print(a)# (1, 2, 3)print(*a)# 1 2 3b = [1,2,3]print(b)# [1, 2, 3]print(*b)# 1 2 3c = {'name':'xufive', 'age':51}print(c)# {'name': 'xufive', 'age': 51}print(*c)# name ageprint('name: {name}, age: {age}'.format(**c))# name: snorlax, age: 24 三元表达式 >>> y = 5>>> print('y是一个负数' if y < 0 else 'y是一个非负数')y是一个非负数 >>> y = 5>>> x = -1 if y < 0 else 1>>> x1 列表推导式 >>> a = [1, 2, 3, 4, 5]>>> result = [i*i for i in a]>>> result[1, 4, 9, 16, 25] 列表索引 >>> a = [0, 1, 2, 3, 4, 5]>>> b = ['a', 'b']>>> a[2:2] = b>>> a[0, 1, 'a', 'b', 2, 3, 4, 5]# 2-2=0 在a[2]的位置插入b>>> a[3:6] = b>>> a[0, 1, 'a', 'a', 'b', 4, 5]# 6-3=3 将a[3:6]三个元素替换为b lambda函数 >>> a = [{'name':'B', 'age':50}, {'name':'A', 'age':30}, {'name':'C', 'age':40}]>>> sorted(a, key=lambda x:x['name']) # 按姓名排序[{'name': 'A', 'age': 30}, {'name': 'B', 'age': 50}, {'name': 'C', 'age': 40}]>>> sorted(a, key=lambda x:x['age']) # 按年龄排序[{'name': 'A', 'age': 30}, {'name': 'C', 'age': 40}, {'name': 'B', 'age': 50}] a = [1,2,3]for item in map(lambda x:x*x, a): print(item, end=', ')1, 4, 9, yield def get_square(n): for i in range(n):yield(pow(i,2))a = get_square(5)# a for i in a: print(i, end=', ')print('-'*8)for i in a: print(i, end=', ')0, 1, 4, 9, 16, -------- 装饰器 import timedef timer(func): def wrapper(*args,**kwds):t0 = time.time()func(*args,**kwds)t1 = time.time()print('耗时%0.3f'%(t1-t0,)) return wrapper@timerdef study(delay): print('函数study开始') time.sleep(delay) print('函数study结束') ? study(3)函数do_something开始函数do_something结束耗时3.004 timer() 是我们定义的装饰器函数，使用@把它附加在任何一个函数（比如study）定义之前，就等于把新定义的函数，当成了装饰器函数的输入参数。运行 study() 函数，可以理解为执行了timer(study)。细节虽然复杂，不过这么理解不会偏差太大，且更易于把握装饰器的制造和使用。
assert 所谓断言，就是声明表达式的布尔值必须为真的判定，否则将触发 AssertionError 异常。严格来讲， assert是调试手段，不宜使用在生产环境中，但这不影响我们用断言来实现一些特定功能，比如，输入参数的格式、类型验证等。
def i_want_to_sleep(delay): assert(isinstance(delay, (int,float))), '函数参数必须为整数或浮点数' print('开始睡觉') time.sleep(delay) print('睡醒了')>>> i_want_to_sleep(1.1)开始睡觉睡醒了>>> i_want_to_sleep(2)开始睡觉睡醒了>>> i_want_to_sleep('2')Traceback (most recent call last):File "", line 1, in i_want_to_sleep('2')File "", line 2, in i_want_to_sleepassert(isinstance(delay, (int,float))), '函数参数必须为整数或浮点数'AssertionError: 函数参数必须为整数或浮点数 Utilities ARGS import argparseparser = argparse.ArgumentParser(description="this is a sample.")parser.add_argument("-n", "--number", default=233, type=int, help="number value.")parser.add_argument("-s", "--string", default='hello', type=str, help="string")parser.add_argument("-t", "--tuple", default=("05", 23), type=tuple, help="tuple")parser.add_argument("-l", "--list", default=[10, "27"], type=list, help="list")args = parser.parse_args()print(args.number, args.string, args.tuple, args.list) sub-command # test.pyimport argparsedef build_argparser():parser = argparse.ArgumentParser(prog='PROG')subparsers = parser.add_subparsers(help='sub-command help', dest = 'action')#添加子命令parser_a = subparsers.add_parser('action_a', help='action_a help')parser_b = subparsers.add_parser('action_b', help='action_b help')# 设置子命令参数 action_aparser_a.add_argument("-i", "--i", type=int, help="i int")parser_a.add_argument("-j", "--j", type=int, help="j int")# 设置子命令参数 action_bparser_b.add_argument("-x", "--x", type=int, help="x int")parser_b.add_argument("-y", "--y", type=int, help="y int")return parserargs = build_argparser().parse_args()if args.action == 'action_a':print(f"{args.i}+{args.j}={args.i+args.j}")elif args.action == 'action_b':print(f"{args.x}*{args.y}={args.x*args.y}") ? python test.py action_a -i 5 -j 105+10=15? python test.py action_b -x 5 -y 105*10=50 sys.argv[] import sysprint(sys.argv[:]) ?python study.py -a 111 -bb two['study.py', '-a', '111', '-bb', 'two'] Write Record File TXT def list2txt(txt_list, txt_file):with open(txt_file, mode='w') as f:for item in txt_list:f.write(f"{item}\n")def dict2txt(txt_dict, txt_file):with open(txt_file, 'w') as f:for i in txt_dict:print(f"{i} {txt_dict[i]}\n", end="")f.write(f"{i} {txt_dict[i]}\n")def txt2list(txt_file):txt_list = []with open(txt_file, "r") as f:for line in f.readlines():line = line.strip('\n')#去掉列表中每一个元素的换行符txt_list.append(line)return txt_list JSON def dict2json(json_dict, json_path):import jsonwith open(json_path,'w') as f:f.write(json.dumps(json_dict, ensure_ascii=False, indent=2))passdef json2dict(json_path:str):import jsonwith open(json_path,'r', encoding='UTF-8') as f:load_dict = json.load(f)return load_dictdef view_dict(json_dict:dict):for key,value in json_dict.items():print('{key} {value}'.format(key = key, value = https://tazarkount.com/read/value))if __name__ =="__main__":json_dict = {}var = "a"json_dict[var] = 1# {'a': 1}json_dict["b"] = 2# {'a': 1, 'b': 2}dict2json(json_dict)print(json2dict('./output.json')) × output.json
{"a": 1,"b": 2} Filename splitext >>> import os>>> a = "1/2/3/4/5/6.txt">>> os.path.splitext(a)# 提取扩展名('1/2/3/4/5/6', '.txt')>>> basename >>> import os>>> a = "1/2/3/4/5/6.txt"# 提取文件名>>> os.path.basename(a)'6.txt'>>> Win or Linux or OSX import sysimport platform print(sys.platform)def ShowPlatform():print ("--------------Operation System-----------------------")print(platform.architecture())print(platform.platform())print(platform.system())# print(platform.uname())print ("--------------Python Version-------------------------")print(platform.python_version()) def UsePlatform():print ("--------------Platform Version-----------------------")sysstr = platform.system()if sysstr == "Windows":print ("Call Windows tasks")elif sysstr == "Linux":print ("Call Linux tasks")else:print ("Call System tasks: %s" % sysstr)return sysstrShowPlatform()UsePlatform() Win10
win32--------------Operation System-----------------------('64bit', 'WindowsPE')Windows-10-10.0.18362-SP0Windows--------------Python Version-------------------------3.7.3--------------Platform Version-----------------------Call Windows tasks Linux
linux--------------Operation System-----------------------('64bit', 'ELF')Linux-5.4.0-40-generic-x86_64-with-glibc2.10Linux--------------Python Version-------------------------3.8.3--------------Platform Version-----------------------Call Linux tasks MacOS
darwin--------------Operation System-----------------------('64bit', '')Darwin-19.6.0-x86_64-i386-64bitDarwin--------------Python Version-------------------------3.7.6--------------Platform Version-----------------------Call System tasks: Darwin