列表，元组等学习笔记小结

例1：列表切片
  names = ["zhangsna","lisi","wangwu","zhaoliu"]
  print(names[1])    #读取第2个元素，列表的下表是从0开始的   lisi
  print(names[0],names[2]) #读取第1个，第3个元素       zhangsna wangwu
  print(names[0:])   #读取下标0及往后的所有元素     ['zhangsna', 'lisi', 'wangwu', 'zhaoliu']
  print(names[1:])   #读取下标1及往后的所有元素    ['lisi', 'wangwu', 'zhaoliu']
  print(names[1:2])   #读取下标1及下标2前的所有元素   ['lisi']
  print(names[1:3])   #读取下标1及下标3前不包括3，这叫切片 ['lisi', 'wangwu']
  print(names[-1])   #读取最后1个元素      zhaoliu
  print(names[-3:])   #读取倒数第三个往后的所有数据；   ['lisi', 'wangwu', 'zhaoliu']
  print(names[-3:-1])   #顺序都是从左往右的      ['lisi', 'wangwu']
  print(names[:3])       #等于names[0:3]       ['zhangsna', 'lisi', 'wangwu']
  print(names[0:-1:2])        #步长2，隔开切片      ["zhangsna","wangwu"]
  print(names[::2])   #等于names[0:-1:2]      ["zhangsna","wangwu"]
 
 
 列2：列表的追加：（追加是追加在末尾）
  names = ["zhangsna","lisi","wangwu","zhaoliu"]
  print(names)          
  names.append("kitty")
  print(names)
 输出结果：
  ['zhangsna', 'lisi', 'wangwu', 'zhaoliu']
  ['zhangsna', 'lisi', 'wangwu', 'zhaoliu', 'kitty']
 
 列3：插入到指定位置：
  names = ["zhangsna","lisi","wangwu","zhaoliu"]
  print(names)
  names.insert(1, "kitty")
  print(names)
 输出结果：
  ['zhangsna', 'lisi', 'wangwu', 'zhaoliu']
  ['zhangsna', 'kitty', 'lisi', 'wangwu', 'zhaoliu']
 
 列4：修改列表内容；
  names = ["zhangsna","lisi","wangwu","zhaoliu"] 
  print(names)
  names[1] = "Brace"
  print(names)
 输出结果：
  ['zhangsna', 'lisi', 'wangwu', 'zhaoliu']
  ['zhangsna', 'Brace', 'wangwu', 'zhaoliu']
 
 
 列5：列表内容的删除：
 删除1：
  names = ["zhangsna","lisi","wangwu","zhaoliu"] 
  print(names)
  names.remove("lisi")
  print(names)         #输出：['zhangsna', 'wangwu', 'zhaoliu']
 删除2：
  print(names)
  del names[1]         #指定下标删除
  print(names)         #输出：['zhangsna', 'wangwu', 'zhaoliu']
 删除3：
  names = ["zhangsna","lisi","wangwu","zhaoliu"] 
  print(names)
  names.pop()          #默认不输入下标，删除最后一个
  print(names)         #输出：['zhangsna', 'lisi', 'wangwu']
 删除4：
  print(names)
  names.pop(1)         #指定下标删除
  print(names)         #['zhangsna', 'wangwu', 'zhaoliu']

 列6：查找元素的下标：
  names = ["zhangsna","lisi","wangwu","zhaoliu"]
  print(names.index("lisi"))      #输出：1
  print(names[names.index("lisi")])    #输出：lisi
 
 
 列7：列表相同元素个数统计： 
  names = ["zhangsna","lisi","wangwu","zhaoliu","lisi"]
  print(names.count("lisi"))      #输出：2

 
 列8： 列表元素的清除
  names = ["zhangsna","lisi","wangwu","zhaoliu","lisi"]
  names.clear()
  print(names)          #输出：[]
 
 列9：列表元素的反转：
  names = ["zhangsna","lisi","wangwu","zhaoliu","lisi"]
  names.reverse()
  print(names)          #输出：['lisi', 'zhaoliu', 'wangwu', 'lisi', 'zhangsna']
 

 列10：列表元素的排序
  names = ["zhangsna","lisi","wangwu","zhaoliu","lisi"]
  names.sort()
  print(names)          #输出：['lisi', 'lisi', 'wangwu', 'zhangsna', 'zhaoliu']
 
 
 列11：列表元素合并： 
  names = ["zhangsna","lisi","wangwu","zhaoliu","lisi"]
  names1 = [1,2,3,4,5]
  names.extend(names1)
  print(names)          #输出：['zhangsna', 'lisi', 'wangwu', 'zhaoliu', 'lisi', 1, 2, 3, 4, 5]
  print(names1)          #输出：[1, 2, 3, 4, 5]
 
 
 列12：列表元素浅复制（浅拷贝）：只拷贝第一层，更深层次不拷贝，和copy.copy一样
 
 列1：
  names = ["zhangsna","lisi","wangwu","zhaoliu","lisi"]
  names2 = names.copy()
  print(names)
  print(names2)
  names[2]="李李"
  print(names)
  print(names2)
 
 输出结果：
  ['zhangsna', 'lisi', 'wangwu', 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', 'wangwu', 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', '李李', 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', 'wangwu', 'zhaoliu', 'lisi']
  
 列2：
  names = ["zhangsna","lisi","wangwu",["a","b","c"],"zhaoliu","lisi"]
  names2 = names.copy()
  print(names)
  print(names2)
  names[2]="李李"
  names[3][1]="bbbbb"
  names[3][2]="ccccc"
  print(names)
  print(names2)
 
 输出结果：
  ['zhangsna', 'lisi', 'wangwu', ['a', 'b', 'c'], 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', 'wangwu', ['a', 'b', 'c'], 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', '李李', ['a', 'bbbbb', 'ccccc'], 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', 'wangwu', ['a', 'bbbbb', 'ccccc'], 'zhaoliu', 'lisi']
 
 要想完整拷贝，需要用到copy模块， copy.deepcopy 深拷贝：
 
  import copy
  names = ["zhangsna","lisi","wangwu",["a","b","c"],"zhaoliu","lisi"]
  names2 = copy.deepcopy(names)
  print(names)
  print(names2)
  names[2]="李李"
  names[3][1]="bbbbb"
  names[3][2]="ccccc"
  print(names)
  print(names2)
 
 输出结果：
  ['zhangsna', 'lisi', 'wangwu', ['a', 'b', 'c'], 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', 'wangwu', ['a', 'b', 'c'], 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', '李李', ['a', 'bbbbb', 'ccccc'], 'zhaoliu', 'lisi']
  ['zhangsna', 'lisi', 'wangwu', ['a', 'b', 'c'], 'zhaoliu', 'lisi']
 
 
 列13：列表循序：
  names = ["zhangsna","lisi","wangwu",["a","b","c"],"zhaoliu","lisi"]
  for i in names:
  print(i)
  
  输出：
  zhangsna
  lisi
  wangwu
  ['a', 'b', 'c']
  zhaoliu
  lisi
 

 浅拷贝的4种实现方式：
  person = ["name",['a',100]]
  方式1：
  P1 = copy.copy(person)
  方式2：
  p2 = person[:]
  方式3：
  p2 = person.copy()
  方式4：
  p3 = list(person)
 
  names = ["zhangsna","lisi","wangwu",["a","b","c"],"zhaoliu","lisi"]
  p1 = list(names)
  names[3][1] = 100
  print(p1)
  
  输出：
  ['zhangsna', 'lisi', 'wangwu', ['a', 100, 'c'], 'zhaoliu', 'lisi'] 

 浅拷贝的应用（联合账号）： 
  person = ["name",["saving",100]]
  p1 = person.copy()
  p2 = person.copy()
  p1[0] = 'alex'
  p2[0] = 'fengjie'
 
  p1[1][1] = 50
  p2[1][1] = 30
  print(p1)
  print(p2)
 输出结果：
  ['alex', ['saving', 30]]
  ['fengjie', ['saving', 30]]

8. 元组tuple：只读列表，不能增删改；
 
 names = ('alex','jack')
 
 只有2个方法，一个是count,一个是index.
 
  
9. 删除变量：
 del name1
 

10.集合set 用于去重；
 >>> ids = [1,2,3,1,3,1,4,5,1,2,3]
 >>> id = list(set(ids))
 >>> id
 [1, 2, 3, 4, 5]
 >>> print(set(ids))
 {1, 2, 3, 4, 5}