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python基础_集合、文件操作

时间:2017-05-27 22:27:15      阅读:254      评论:0      收藏:0      [点我收藏+]

标签:att   差集   style   isa   ima   dex   部分   高效   readline   

集合

集合是一个无序的且数据不会重复。有去重、关系测试的作用

list = ["11","22","33","44","55"]
list = set(list)
print(list,type(list))
结果为:
{33, 11, 22, 55, 44} <class set>
关系测试
list1 = set(["11","22","33","44","55"]) list2 = set(["55","66","77","88","99"]) list3 = set(["11","22"]) #list = set(list) print(list1,type(list)) #交集 print(list1.intersection(list2)) #并集 print(list1.union(list2)) #差集 print(list1.difference(list2))#list1 有,list2没有 #子集 print(list1.issubset(list2))# False print(list3.issubset((list1))) #True
print(list1.isdisjoint(list2))#没有交集
#反相差集
print(list1.symmetric_difference(list2))#把不是交集部分取出
结果为:
{55, 44, 11, 22, 33} <class type>
{55}
{11, 22, 66, 44, 33, 88, 77, 99, 55}
{44, 11, 22, 33}
False
True
{11, 66, 22, 33, 88, 77, 99, 44}

 

文件操作

技术分享
f = open("test","r",encoding= "utf-8")
data = f.read()
data2 = f.read()
print(data)
print("-----data2-----%s"%data)
读r
技术分享
f = open("test","w",encoding= "utf-8")
f.write("北京")
f.write("天安门")
写w
技术分享
f1 = open("test","a",encoding="utf-8")#追加,只能写
f1.write("lalala")
追加a
技术分享
f = open ("test","r",encoding="utf-8")
print(f.readline())
print(f.readline())
print(f.readline())#按行读

或
f = open ("test","r",encoding="utf-8")
for i in range(5):
    print(f.readline())#按行读
按行读readline
技术分享
f = open ("test","r",encoding="utf-8")
print(f.readlines())#每行为一个元素,打印出整个列表
结果:
[第一句话北京天安门lalala\n, 第二句呼啦啦哗啦啦\n, 第三句规定不到佛]

f = open ("test","r",encoding="utf-8")
for i in f.readlines():#打印出每一行的元素,就是打印整个文件
    print(i)
readlines
技术分享
f = open ("test","r",encoding="utf-8")
for i in f:#一行行的读,读完并释放内存,高效
    print(i)


f = open ("test","r",encoding="utf-8")
for index,line in enumerate(f.readlines()):#将文件转换成列表
    if index == 1:
        print("跳过")
    else:
        print(line)
循环读取
技术分享
f = open ("test","r",encoding="utf-8")
print(f.readline(),"读到第一行")
print(f.read())#从第二行读取
f.seek(0) #光标移回第一行,可重新开始读
print(f.read())
seek,tell按字符结束
其他方法
encoding
f = open ("test","r",encoding="utf-8")
print(f.encoding)#打印文件的编码

fileno
f = open ("test","r",encoding="utf-8")
print(f.fileno())#文件句柄在操作系统的编号

f = open ("test","r",encoding="utf-8")
print(f.isatty())#判断是不是终端设备

 

 

技术分享
f = open("test","r+",encoding="utf-8")#读和追加模式
print(f.readline())
f.write("\n******")
print(f.readline())
r+
技术分享
f = open("test","w+",encoding="utf-8")#写读,先创建文件 
f.write("******\n")
f.write("******\n")
f.write("******\n")
f.write("******\n")
print(f.readline())
print(f.tell())
f.write("1******")
print(f.readline())
w+
技术分享
f = open("test","rb")#以二进制去读,不要添加,encoding="utf-8"
print(f.readline())
rb
技术分享
f = open("test","wb")#以二进制去读,不要添加,encoding="utf-8"
f.write("噜啦噜啦啦欧拉".encode())
wb

 文件替换

技术分享

技术分享
#with
with open("test","r",encoding="utf-8") as f:
    print(f.readline())
    for line in f:
        print(line.strip())
with
#打开多个文件
with open("test","r",encoding="utf-8") as f,\
open("test","r",encoding="utf-8"):

python基础_集合、文件操作

标签:att   差集   style   isa   ima   dex   部分   高效   readline   

原文地址:http://www.cnblogs.com/wengxq/p/6819044.html

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