python_day8

今天的学习以代码的形式开展:

##字典相关函数
dic = {}
#增
#1.普通方法
dic["top"] = "369"
dic["mid"] = "left"
print(dic)

#2.formkeys使用一组键和默认值创建字典
tup = ("a","b","c")
#fromkeys (盛放键的容器，默认值)
dic={}.fromkeys(tup,None)
print(dic)

#注意点 字典中的三个键默认指向史一个列表


#删
dic = {'top': '369', 'mid': 'left',"bottom":"jacklove"}
res = dic.pop("mid")
print(res)
print(dic)
#可以给pop设置第二个参数 ， 以防止键不存在时报错
res = dic.pop("adc","不存在")
print(res)

#popitem() 删除最后一个键值对
dic = {'top': '369', 'mid': 'left',"bottom":"jacklove"}
res = dic.popitem()
print(res)
print(dic)

#clear 清空字典

dic.clear()
print(dic)

#改
#updata  批量更新，有就更新，没键就添加

#没键添加
dic = {'top': '369', 'mid': 'left',"bottom":"jacklove"}
dic_new = {"jungle":"ning","support":"baolan"}
dic.update(dic_new)
print(dic)

#有就更新
dic_new = {"top":"the shy","xiaochang":"王思聪"}
dic.update(dic_new)

#了解
dic.update(ww="王文")
print(dic)

#get 通过键获取值（若没有改建可设置默认值，预防报错）
#get 在获取字典键时，如果不存在。不会报错，返回none
dic_new = {"top":"the shy","xiaochang":"王思聪"}
res = dic["top"]
res = dic.get("top")
print(res)
#给与默认值提示
res = dic.get("123","不存在")
print(res)


#keys()获取键		
dic = {"top":"the shy","xiaochang":"王思聪"}
res = dic.keys()
print(res,type(res))

for i in res:
    print(i)

#values()获取值	
res = dic.values()
print(res,type(res))

    
	
	
#item()		获取键和值
res = dic.items()
print(res,type(res))

for i in res:
    print(i)
    
for k,v in res:
    print(k,v)

#集合相关操作(交，差，并，补)
    
#intersection 交集
set1 = {"旭旭宝宝","pdd","五五开","云烨"}
set2 = {"刘备","关羽","张飞","马超","云烨"}

res = set1.intersection(set2)
print(res)
#简写 &
res = set1 & set2
print(res)

#差集
res = set1.difference(set2)
print(res)
#简写 -
res = set1 - set2
print(res)

#并 union()
res = set1.union(set2)
print(res)

#简写 |
res = set1|set2
print(res)

#symmetric_difference 对称差集(补集蕴含其中)
res = set1.symmetric_difference(set2)
print(res)

#简写
res = set1^set2
print(res)

#issubset 是否是子集
set1 = {"刘德华","郭富城","张学友","郭富城","云烨"}
set2 = {"云烨"}
res = set1.issubset(set2)
print(res)

#简写
res = set2 <= set1
print(res)

#issuperset 是否是父集
set1 = {"刘德华","郭富城","张学友","郭富城","云烨"}
set2 = {"云烨"}
res = set1.issuperset(set2)
print(res)

#简写
res = set1>set2
print(res)

#isdisjoint 检测两集合是否不相交  不相交ture  相交false
set1 = {"刘德华","郭富城","张学友","郭富城","云烨"}
set2 = {"云烨"}
res = set1.isdisjoint(set2)
print(res)

##集合相关函数
#增
#add 一次加一个  数据
set1 = {"云烨"}
set1.add("柳月")
print(set1)

#updata()迭代增加	一次加一堆
set1 = {"云烨"}
lst = ["a","b"]
set1.update(lst)
print(set1)


#删
#clear 清空
setvar = {"刘德华","郭富城","张学友","郭富城","云烨"}
setvar.clear()
print(setvar)
#pop 随机删除一个
setvar = {"刘德华","郭富城","张学友","郭富城","云烨"}
res = setvar.pop()
print(res)
print(setvar)

#discard  删除集合中指定的值(不存在不删除)
setvar = {"刘德华","郭富城","张学友","郭富城","云烨"}
setvar.discard("1")
print(setvar)

#remove 删除集合中指定的值（不存在报错）
setvar = {"刘德华","郭富城","张学友","郭富城","云烨"}


#冰冻集合
#frozenset 单纯只能做交差并补操作，不能做添加或者删除的操作
lst = ["1","2","3"]
fzl = frozenset(lst) 
print(fzl)


#fp = open(文件,模式,编码集) fp => 文件的io对象(文件句柄)‘
#i => input 输入 o => outpur 输出
#fp.read()读取文件内容 fp.write()写入文件的内容
# 1.文件的写入操作


# 2.文件的读取操作
# (1)打开文件
# (2) 读取内容 res = fp.read()
# (3) 关闭文件 fp.close () print(res)
#文件模式

#打开
fp = open("1.txt",mode="w",encoding="utf-8")
#写入
fp.write("111")
#关闭
fp.close()

fp = open("1.txt",mode="r",encoding="utf-8")

res = fp.read()

fp.close()

#二进制字节流
#b b开头的字节流只能是ascii编码中的字符不能是中文
#encode  编码  将字符串编程字节流   
#decode 解码  将字节流转换成字符串
data = b"abc"
print(data,type(data))

data = "中文".encode("utf-8")
print(data,type(data))
res =data.decode("utf-8")
print(res)

#utf-8 一个中文 3个字节
data = "中文".encode("utf-8")
print(len(data))
#中文字节流进行反解
res = b'\xe4\xb8\xad\xe6\x96\x87'.decode()
print(res)

#文件存储二进制的字节流
"""如果存储二进制字节流，指定模式wb，不指定encoding编码集，否则报错"""
fp = open("2.txt",mode="wb")
strvar = "云烨".encode()
fp.write(strvar)
fp.close()



#复制文件集合.png
#所有的图片、音频、视频都需要通过二进制来进行存储

#先把源文件子文件字节流读取出来
#相对路径
fp = open("1.png",mode ="rb")
#绝对路径
fp = open(r"D:\Cloud\Python\day_01\1.png",mode= "rb")
res = fp.read()
fp.close()
#计算文件中的字节个数
print(len(res))
#再把二进制字节流写到另一个文件中，相当于复制
fp = open("2.png",mode="wb")
fp.write(res)
fp.close()



#utf-8编码中  一个中文3个字节，一个英文或符号一个字节
#read()  读取字符个数 当前光标右读
#seek    调整指针位置  seek（0） 移动到0字节位置
                    # seek（0，2） 移动到文件末尾
#tell     当前光标左侧字节数


#文件操作的扩展模式
#r+先读后写     
#先读
fp = open("3.txt",mode="r+",encoding="utf-8")
res = fp.read()
print(res)
#在写
fp.write("ab")
#再读
res = fp.read()
print(res)
fp.close()


#先写后读
fp = fp = open("3.txt",mode="r+",encoding="utf-8")
#移动光标到最后,否则r模式下，原字符被覆盖
fp.seek(0,2)
fp.write("cd")
#再读
fp.seek(0)
res = fp.read()

fp.close()

#3 w+ 可读可写，清空重写 默认可以创建新的文件
fp = open("4.txt",mode="w+",encoding="utf-8")
fp.write("abc")
fp.seek(0)
print(fp.read())
fp.close()

#4 a+  可读可写 ，追加写入
# append 

fp = open("5.txt",mode="a+",encoding="utf-8")
fp.write("def")
fp.seek(0)
res = fp.read()
print(res)
fp.close()


#5.r+和a+区别

"""r+模式基于当前光标位置进行写入覆盖
   a+模式会强制把光标放到文件末尾进行追加
   读模式没有区别
"""
fp = open("5.txt",mode="a+",encoding="utf-8")
fp.seek(3)#第三个字节的位置
fp.write("zxc")
fp.close()

fp = open("5.txt",mode="r+",encoding="utf-8")
fp.seek(3)#第三个字节的位置
fp.write("zxc")
fp.close()

#6.seek tell read 之间的使用
fp = open("5.txt",mode="r+",encoding="utf-8")
fp.seek(4)
#telpp 当前光标左边所有内容的字节数
res = fp.tell()
print(res)

#在r+模式下 read（2）代表读取两个字符，在rb模式下read（2）代表读取两个字节


#7.注意点(seek 在移动到某个汉字的字节中间，导致字节无法解析)
fp = open("6.txt",mode="r+",encoding="utf-8")
fp.seek(3)
fp.close()

#8.with 语句 自动实现文件关闭操作  as 起别名

with open("1.png",mode ="rb") as fp:
    res = fp.read()
with open("2.png",mode ="wb") as fp:
    fp.write(res)

#继续简化
with open("1.png",mode ="rb") as fp1,open("2.png",mode ="wb") as fp2:
    res = fp1.read()
    fp2.write(res)