Python - 练习
目录
单例设计模式
class Dog(object):
# 保存单例引用
singleton = None
# 初始化一次的标记
init_flag = False
# 分配内存空间
def __new__(cls, *args, **kwargs):
if cls.singleton is None:
# 调用父类方法创建空间，返回引用
cls.singleton = super().__new__(cls)
print('__new__ run...')
# 返回引用给__init__ 进行初始化
return cls.singleton
def __init__(self):
if Dog.init_flag:
return
print('初始化 run...')
Dog.init_flag = True
dog1 = Dog()
print(dog1)
dog2 = Dog()
print(dog2)
"""
__new__ run...
初始化 run...
<__main__.Dog object at 0x000002227BA43EB0>
__new__ run...
<__main__.Dog object at 0x000002227BA43EB0>
"""
打印长方形
"""
需求在控制台打印如下图形：
*********
*********
*********
*********
*********
*********
*********
*********
*********
"""
# 大圈，控制行号
row = 1
while row <= 9:
col = 1
# 小圈控制列
while col <= 9:
print("*", end="")
col += 1
print("")
row += 1
打印九九乘法表
# while 写法
row = 1
while row <= 9: # 大圈，控制行号
col = 1
while col <= row: # 小圈控制列 , 注意col < row
print(f"{col} * {row} = {col * row}", end="\t")
col += 1
print("")
row += 1
# for循环写法:
for x in range(1, 10):
for y in range(1, x + 1):
print(f"{y} * {x} = {y * x}", end="\t")
print("")
输出：
1 * 1 = 1
1 * 2 = 2 2 * 2 = 4
1 * 3 = 3 2 * 3 = 6 3 * 3 = 9
1 * 4 = 4 2 * 4 = 8 3 * 4 = 12 4 * 4 = 16
1 * 5 = 5 2 * 5 = 10 3 * 5 = 15 4 * 5 = 20 5 * 5 = 25
1 * 6 = 6 2 * 6 = 12 3 * 6 = 18 4 * 6 = 24 5 * 6 = 30 6 * 6 = 36
1 * 7 = 7 2 * 7 = 14 3 * 7 = 21 4 * 7 = 28 5 * 7 = 35 6 * 7 = 42 7 * 7 = 49
1 * 8 = 8 2 * 8 = 16 3 * 8 = 24 4 * 8 = 32 5 * 8 = 40 6 * 8 = 48 7 * 8 = 56 8 * 8 = 64
1 * 9 = 9 2 * 9 = 18 3 * 9 = 27 4 * 9 = 36 5 * 9 = 45 6 * 9 = 54 7 * 9 = 63 8 * 9 = 72 9 * 9 = 81
一行代码打印九九乘法表
"""
注意：
1.左边for循环可以访问右边for循环的变量。
2.右边for不能访问左边for循环的变量
"""
# 正确写法
print("\n".join([" ".join(f"{x}*{y} = {x * y}" for y in range(1, x + 1)) for x in range(1, 10)]))
# 此类写法错误
data1 = "\n".join([" ".join(f"{x} * {y} = {x * y}" for x in range(1, 10)) for y in range(1, x+1)])
print(data1)
解析:
print(" ".join(f"{x}" for x in range(1, 10)))
# out:1 2 3 4 5 6 7 8 9
print([" ".join(f"{x} * {y} = {x*y}" for x in range(1, y+1)) for y in range(1, 10)])
# out:
['1 * 1 = 1', '1 * 2 = 2 2 * 2 = 4', '1 * 3 = 3 2 * 3 = 6 3 * 3 = 9', '1 * 4 = 4 2 * 4 = 8 3 * 4 = 12 4 * 4 = 16', '1 * 5 = 5 2 * 5 = 10 3 * 5 = 15 4 * 5 = 20 5 * 5 = 25', '1 * 6 = 6 2 * 6 = 12 3 * 6 = 18 4 * 6 = 24 5 * 6 = 30 6 * 6 = 36', '1 * 7 = 7 2 * 7 = 14 3 * 7 = 21 4 * 7 = 28 5 * 7 = 35 6 * 7 = 42 7 * 7 = 49', '1 * 8 = 8 2 * 8 = 16 3 * 8 = 24 4 * 8 = 32 5 * 8 = 40 6 * 8 = 48 7 * 8 = 56 8 * 8 = 64', '1 * 9 = 9 2 * 9 = 18 3 * 9 = 27 4 * 9 = 36 5 * 9 = 45 6 * 9 = 54 7 * 9 = 63 8 * 9 = 72 9 * 9 = 81']
字符串find 和 index 方法的区别
find(el): 找不到的时候不会由异常，返回-1
index(el): 找不到的时候会抛出异常，ValueError: substring not found
[{},{},{}] 调整为[(),(),()]
使用场景：读取json文件，使用parameterized 做参数化
def build_data(filepath):
"""
功能：读取json文件组装成[(), (), ()]格式的数据
:param filepath: 指定处理的json文件
:return: 组装完成的列表数据
"""
# 读取json数据
my_list = []
with open(filepath, encoding='utf-8') as f:
dict_data = json.load(f)
print(dict_data)
for x in dict_data:
# 方式一：
# tup_gen = (y for y in x.values())
# my_tup = tuple(tup_gen)
# 方式二：
my_tup = tuple(x.values())
my_list.append(my_tup)
return my_list
if __name__ == '__main__':
ret = build_data('./login.json')
print(tuple(ret))
print(*tuple(ret))
# out:
"""
[{'desc': '登陆成功', 'mobile': '13800000002', 'password': '123456', 'status_code': 200, 'success': True, 'code': 10000, 'message': '操作成功'},
{'desc': '用户名错误', 'mobile': '1380003342', 'password': '123456', 'status_code': 200, 'success': False, 'code': 20001, 'message': '用户名或密码错误'}]
[('登陆成功', '13800000002', '123456', 200, True, 10000, '操作成功'), ('用户名错误', '1380003342', '123456', 200, False, 20001, '用户名或密码错误')]
"""
[{},{},{}] 调整为((),(),())
场景：
[{},{},{}] 一般是json.load() 的数据格式，但是测试做参数化的时候使用不是该格式，所以需要转化为如下格式：
- parameterized 使用的数据格式是[(),(),()] 【上面实现过】
- ddt 使用的数据格式是(),(),() 【可以将((),(),()) 拆包】
需求：
如何将[{},{},{}] 转换为(),(),()
实现：将[{},{},{}] 转换为((),(),()), 然后进行拆包操作
"""
# read_json_data.py
def build_data(filepath):
"""
功能：读取json文件组装成[(), (), ()]格式的数据
:param filepath: 指定处理的json文件
:return: 组装完成的列表数据
"""
# 读取json数据
my_list = []
with open(filepath, encoding='utf-8') as f:
data = json.load(f)
print(data)
for x in data:
my_tup = tuple(x.values())
my_list.append(my_tup)
return my_list
if __name__ == '__main__':
ret = build_data('./login.json')
print(tuple(ret))
print(*tuple(ret))
# out:
"""
(('登陆成功', {'mobile': '13800000002', 'password': '123456'}, {'status_code': 200, 'success': True, 'code': 10000, 'message': '操作成功'}), ('用户名错误，登陆失败', {'mobile': '13800003342', 'password': '123456'}, {'status_code': 200, 'success': False, 'code': 20001, 'message': '用户名或密码错误'}), ('密码错误，登陆失败', {'mobile': '13800000002', 'password': '123456abc'}, {'status_code': 200, 'success': False, 'code': 20001, 'message': '用户名或密码错误'}))
('登陆成功', {'mobile': '13800000002', 'password': '123456'}, {'status_code': 200, 'success': True, 'code': 10000, 'message': '操作成功'}) ('用户名错误，登陆失败', {'mobile': '13800003342', 'password': '123456'}, {'status_code': 200, 'success': False, 'code': 20001, 'message': '用户名或密码错误'}) ('密码错误，登陆失败', {'mobile': '13800000002', 'password': '123456abc'}, {'status_code': 200, 'success': False, 'code': 20001, 'message': '用户名或密码错误'})
"""
# test.py
import unittest
import ddt
from ni01_eai_login_api import LoginApi
from read_json_data import build_data
# 读取测试用例数据
test_data = tuple(build_data('./login.json'))
@ddt.ddt
class TestLogin(unittest.TestCase):
# @ddt.data((1, {'hhh': 'xxxx'}, {'qqq': 'www'}), (1, {'hhh': 'xxxx'}, {'qqq': 'www'}))
@ddt.data(*test_data)
@ddt.unpack
def test_01(self, title, body, expect):
print(f"title is {title}, body is {body}, expect is {expect}" )
if __name__ == '__main__':
unittest.main()
找到列表中两个不同元素的最大积
>>>l = [-10,3,2,7,8]
>>> from itertools import combinations
>>> combinations(l, 2)
<itertools.combinations object at 0x0000022385A34B30>
>>> list(combinations(l,2))
[(-10, 3), (-10, 2), (-10, 7), (-10, 8), (3, 2), (3, 7), (3, 8), (2, 7), (2, 8), (7, 8)]
>>> max(a*b for a,b in combinations(l,2))
56
https://zhuanlan.zhihu.com/p/343374115本文来自博客园，作者：chuangzhou，转载请注明原文链接：https://www.cnblogs.com/czzz/p/15782264.html
