python第三课

曾经终败给现在 2022-06-01 07:05 413阅读 0赞

\# 集合  
list\_1 = \[1, 4, 5, 7, 3, 6, 7, 9\]  
list\_1 = set(list\_1)  
  
list\_2 = set(\[4, 6, 0, 66, 22, 8\])  
print(list\_1, type(list\_1))  
  
print(list\_1.intersection(list\_2))   \# 交集  
print(list\_1.union(list\_2))   \# 并集  
print(list\_1.difference(list\_2))   \# 差集  
  
list\_3 = set(\[1, 3, 7\])  
print(list\_3.issubset(list\_1))   \# 子集  
print(list\_1.issuperset(list\_3))   \# 父集  
  
print(list\_1.symmetric\_difference(list\_2))   \# 对称差集  
  
list\_4 = set(\[5, 6, 8\])  
print(list\_3.isdisjoint(list\_4))  
  
  
print(list\_1 & list\_2)  \# 交集  
print(list\_1 | list\_2)  \# 并集  
print(list\_1 - list\_2)  \# 差集  
print(list\_1 ^ list\_2)  \# 对称差集  
  
list\_1.add(999)  \# 添加  
list\_1.update(\[888, 777, 555\])  
\# remove 删除

list\_1.discard("888")

\# 文件操作  
f = open("yesterday1", 'r', encoding='utf-8')  \# 文件句柄  
data = f.read()  
print(data)  
f = open("yesterday1", 'w', encoding='utf-8')  \# 文件句柄  
f.write("我爱北京天安门，\\n")  
f.write("天安门上太阳升")  
f = open("yesterday1", 'a', encoding='utf-8')  \# a = append 追加  
f.write("我爱北京天安门。。。。，\\n")  
f.write("天安门上太阳升。。\\n")  
f.write("\\nWhen i was young i listen to the radio\\n")  
data = f.read()  
print("--read", data)  
f.close()  
f = open("yesterday1", 'r', encoding='utf-8')  
\# print(f.readline())  
for line in f.readlines():  
    print(line.strip())  
for i in range(5):  
    print(f.readline())  
for index, line in enumerate(f.readlines()):  
    if index == 9:  
        print("---我是分割线---")  
        continue  
    print(line.strip())  
f.close()  
f = open("yesterday1", 'r', encoding='utf-8')  
count = 0  
for line in f:  
    if count == 9:  
        print("---我是分割线---")  
        count += 1  
        continue  
    print(line)  
f.close()  
f = open("yesterday1", 'r', encoding='utf-8')  
print(f.tell())  
print(f.readline())  
print(f.read(5))  
print(f.tell())  
print(f.readline())  
print(f.readline())  
print(f.tell())  
f.seek(0)  \# 光标移到某个位置  
print(f.readline())  
print(f.tell())  \# 打印当前的光标位置  
  
print(f.fileno())  \# 文件句柄  
print(f.name())  \# 文件名称  
print(f.seekable())  \# 判断光标是否可移动  
print(f.flush())  \# 刷新  
f.close()  
  
import sys, time  
for i in range(20):  
    sys.stdout.write("\#")  
    sys.stdout.flush()  
    time.sleep(0.2)  
  
f = open("yesterday1", 'a', encoding='utf-8')  
f.truncate(20)  \# 截断  
f.close()  
  
f = open("yesterday1", 'r+', encoding='utf-8')    \# 读 追加  
print(f.readline())  
print(f.readline())  
print(f.readline())  
print(f.tell())  
f.write("-----------D---------")  
f.close()  
  
f = open("yesterday1", 'w+', encoding='utf-8')    \# 写 读  
f.write("-----------D---------1\\n")  
f.write("-----------D---------1\\n")  
f.write("-----------D---------1\\n")  
print(f.tell())  
f.seek(10)  
print(f.readline())  
f.write("should be at the begining of the second line")  
f.close()  
a+ 追加读  
rb 二进制读  
wb 二进制写  
  
\# 文件修改  
f = open("yesterday1", "r", encoding="utf-8")  
f\_new = open("yesterday2.bak", "w", encoding="utf-8")  
for line in f:  
    if "肆意的快乐等我享受" in line:  
        line = line.replace("肆意的快乐等我享受", "肆意的快乐等Alex享受")  
    f\_new.write(line)  
f.close()  
f\_new.close()  
  
with open("yesterday2", "r", encoding="utf-8") as f:  
    for line in f:

print(line)

\# 编码转换  
\# -\*-coding:gbk-\*-  
import sys  
print(sys.getdefaultencoding())  
s = "你好"   \# 数据类型是unicode  
print(s.encode("gbk"))  
print(s.encode("utf-8"))  
print(s.encode("utf-8").decode("utf-8").encode("gb2312").decode("gb2312"))  
  
\# 函数与函数式编程  
1.面向对象:类-->class  
2.面向过程:过程-->def  
3.函数式编程:函数-->def  
函数是逻辑结构化和过程的一种编程方法  
def test(x):  
    """The function definitions"""  
    x += 1  
    return x  
def: 定义函数的关键字  
test: 函数名  
():内可定义形参  
"":文档描述（非必要，但是强烈建议为你的函数添加描述信息）  
x+=1:泛指代码块或程序处理逻辑  
return:定义返回值  
\# 函数  
def func1():  
    """testing1"""  
    print('in the func1')  
    return 0  
\# 过程  
def func2():  
    """testing2"""  
    print('in the func2')  
  
x=func1()  
y=func2()  
print('from func1 return is %s' %x)  
print('from func2 return is %s' %y)  
import time  
def logger():  
    time\_format = '%Y-%m-%d %X'  
    time\_current = time.strftime(time\_format)  
    with open('a.txt', 'a+') as f:  
        f.write('end action\\n')  
def test1():  
    print('test1 starting action...')  
    logger()  
def test2():  
    print('test2 starting action...')  
    logger()  
def test3():  
    print('test3 starting action...')  
    logger()  
  
def test1():  
    print('in the test1')  
def test2():  
    print('in the test2')  
    return 0  
def test3():  
    print('in the test3')  
    return 1,'hello',\['alex','wupeiqi'\],\{'name': 'alex'\}  
x = test1()  
y = test2()  
z = test3()  
print(x)  
print(y)  
print(z)  
  
  
def test(x, y, z):  
    print(x)  
    print(y)  
    print(z)  
test(y=2,x=1) \# 与形参顺序无关  
test(1, 2)  \# 与形参一一对应  
test(x=2,3)  
test(3,z=2,y=6)

def test(x,y=2):  
    print(x)  
    print(y)  
test(1)  
test(1,3)  
def test(x,soft1=True,soft2=True):  
    print(x)  
def conn(host,port=3306):  
    pass  
conn()  
\# 默认参数特点：调用函数的时候，默认参数非必须传递  
\# 用途：默认安装值

def test(x,y,z=2):  
    print(x)  
    print(y)  
test(1,2,3)

\# 参数组  
def test(\*args):  
    print(args)  
test(1,2,3,4,5)  
test(\*\[1,2,3,4,5\])   \# args=tuple(\[1,2,3,4,5\])  
\# \*args:接收N个位置参数，转换成元祖形式  
def test1(x,\*args):  
    print(x)  
    print(args)  
test1(1,2,3,4,5,6,7)  
\# \*\*kwargs:把N个关键字参数，转换成字典的方式  
def test2(\*\*kwargs):  
    print(kwargs)  
    print(kwargs\['name'\])  
    print(kwargs\['age'\])  
    print(kwargs\['sex'\])  
test2(name='alex',age=8,sex='N')  
test2(\*\*\{'name':'alex','age':'8'\})  
  
def test3(name,\*\*kwargs):  
    print(name)  
    print(kwargs)  
test3('alex',age=18,sex='m')  
  
def test4(name,age=18,\*\*kwargs):  \# 参数组一定在后面  
    print(name)  
    print(age)  
    print(kwargs)  
test4('alex',sex='m',hobby='tesla',age=3)  
  
def test4(name,age=18,\*args,\*\*kwargs):  
    print(name)  
    print(age)  
    print(args)  
    print(kwargs)

logger("TEST4")  
def logger(source):  
    print("from %s" % source)

test4('alex',age=34,sex='m',hobby='tesla')

\# 局部变量  
\# 函数外定义的变量是全局变量  
school ='oldboy edu.'  
  
def change\_name(name):  
    global school  
    school = 'Mage Linux'  
    print("before change", name,school)  
    name = 'Alex li'  \# 这个函数就是这个变量的作用域  
    print("after change", name)  
name='alex'  
change\_name(name)  
print(name)  
print("school:", school)  
  
  
def change\_name():  
    golbal name      \# 不要这么写程序  
    name = 'alex'  
change\_name()  
print(name)  
  
school ='oldboy edu.'  
names = \['Alex',"Jack","Rain"\]  
names\_tuple = (1,2,3,4)  
def change\_name():  
    names\[0\]="金角大王"  
    print("inside func", names)  
    print(names)  
change\_name()  
print(names)

\# 递归：一个函数在内部调用自己,就叫递归  
\# 1.必须有一个明确的结束条件  
\# 2.每次进入更深一层时，问题规模相比上一次递归应有所减少  
\# 3.递归效率不高  
def calc(n):  
    print(n)  
    return calc(n+1)  
calc(0)  
  
def calc(n):  
    print(n)  
    if int(n/2) > 0:  
        return calc(int(n/2))  
    print("-->", n)  
calc(10)

\# 高阶函数：一个函数可以接收另一个函数作为参数。  
def add(a,b,f):  
    return f(a)+f(b)  
res = add(3, -6, abs)  
print(res)