1.概述
列表是python的基本数据类型之一，是一个可变的数据类型，用[]方括号表示，每一项元素使用逗号隔开，可以装大量的数据
#先来看看list列表的源码写了什么，方法:按ctrl+鼠标左键点list
class list(object): """ list() -> new empty list list(iterable) -> new list initialized from iterable's items """ def append(self, p_object): # real signature unknown; restored from __doc__ """ L.append(object) -- append object to end """ pass def count(self, value): # real signature unknown; restored from __doc__ """ L.count(value) -> integer -- return number of occurrences of value """ return 0 def extend(self, iterable): # real signature unknown; restored from __doc__ """ L.extend(iterable) -- extend list by appending elements from the iterable """ pass def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ """ L.index(value, [start, [stop]]) -> integer -- return first index of value. Raises ValueError if the value is not present. """ return 0 def insert(self, index, p_object): # real signature unknown; restored from __doc__ """ L.insert(index, object) -- insert object before index """ pass def pop(self, index=None): # real signature unknown; restored from __doc__ """ L.pop([index]) -> item -- remove and return item at index (default last). Raises IndexError if list is empty or index is out of range. """ pass def remove(self, value): # real signature unknown; restored from __doc__ """ L.remove(value) -- remove first occurrence of value. Raises ValueError if the value is not present. """ pass def reverse(self): # real signature unknown; restored from __doc__ """ L.reverse() -- reverse *IN PLACE* """ pass def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__ """ L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*; cmp(x, y) -> -1, 0, 1 """ pass def __add__(self, y): # real signature unknown; restored from __doc__ """ x.__add__(y) <==> x+y """ pass def __contains__(self, y): # real signature unknown; restored from __doc__ """ x.__contains__(y) <==> y in x """ pass def __delitem__(self, y): # real signature unknown; restored from __doc__ """ x.__delitem__(y) <==> del x[y] """ pass def __delslice__(self, i, j): # real signature unknown; restored from __doc__ """ x.__delslice__(i, j) <==> del x[i:j] Use of negative indices is not supported. """ pass def __eq__(self, y): # real signature unknown; restored from __doc__ """ x.__eq__(y) <==> x==y """ pass def __getattribute__(self, name): # real signature unknown; restored from __doc__ """ x.__getattribute__('name') <==> x.name """ pass def __getitem__(self, y): # real signature unknown; restored from __doc__ """ x.__getitem__(y) <==> x[y] """ pass def __getslice__(self, i, j): # real signature unknown; restored from __doc__ """ x.__getslice__(i, j) <==> x[i:j] Use of negative indices is not supported. """ pass def __ge__(self, y): # real signature unknown; restored from __doc__ """ x.__ge__(y) <==> x>=y """ pass def __gt__(self, y): # real signature unknown; restored from __doc__ """ x.__gt__(y) <==> x>y """ pass def __iadd__(self, y): # real signature unknown; restored from __doc__ """ x.__iadd__(y) <==> x+=y """ pass def __imul__(self, y): # real signature unknown; restored from __doc__ """ x.__imul__(y) <==> x*=y """ pass def __init__(self, seq=()): # known special case of list.__init__ """ list() -> new empty list list(iterable) -> new list initialized from iterable's items # (copied from class doc) """ pass def __iter__(self): # real signature unknown; restored from __doc__ """ x.__iter__() <==> iter(x) """ pass def __len__(self): # real signature unknown; restored from __doc__ """ x.__len__() <==> len(x) """ pass def __le__(self, y): # real signature unknown; restored from __doc__ """ x.__le__(y) <==> x<=y """ pass def __lt__(self, y): # real signature unknown; restored from __doc__ """ x.__lt__(y) <==> x<y """ pass def __mul__(self, n): # real signature unknown; restored from __doc__ """ x.__mul__(n) <==> x*n """ pass @staticmethod # known case of __new__ def __new__(S, *more): # real signature unknown; restored from __doc__ """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __ne__(self, y): # real signature unknown; restored from __doc__ """ x.__ne__(y) <==> x!=y """ pass def __repr__(self): # real signature unknown; restored from __doc__ """ x.__repr__() <==> repr(x) """ pass def __reversed__(self): # real signature unknown; restored from __doc__ """ L.__reversed__() -- return a reverse iterator over the list """ pass def __rmul__(self, n): # real signature unknown; restored from __doc__ """ x.__rmul__(n) <==> n*x """ pass def __setitem__(self, i, y): # real signature unknown; restored from __doc__ """ x.__setitem__(i, y) <==> x[i]=y """ pass def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__ """ x.__setslice__(i, j, y) <==> x[i:j]=y Use of negative indices is not supported. """ pass def __sizeof__(self): # real signature unknown; restored from __doc__ """ L.__sizeof__() -- size of L in memory, in bytes """ pass __hash__ = None list
2.列表的索引和切片
#列表和字符串一样拥有索引和切片
#索引：下标从0开始
lst = ["赵四","刘能","谢大脚","谢腾飞","小蒙"] print(lst[0]) #获取第一个元素 #赵四 print(lst[1]) #刘能 print(lst[2]) #谢大脚 print(lst[3][2]) #飞 #索引下标从0开始，3就是谢腾飞，2就是在谢腾飞中切012，就是飞 print(lst[-2]) #负就是从后面切，从-1开始，-2就是谢腾飞
#切片
lst = ["赵四","刘能","谢大脚","谢腾飞","小蒙"] print(lst[1:4]) #['刘能','谢大脚','谢腾飞'] #列表和字符串一样，顾头不顾尾，不能切到4print(lst[-3:-1]) #['谢大脚', '谢腾飞'],顾头不顾尾所以不能切到小蒙print(lst[1::2]) #['刘能', '谢腾飞'] #从1开始到结束，每隔2个输出一个print(lst[-1:-5:-2]) #['小蒙', '谢大脚'] #-1到-5，但是顾头不顾尾就不能切到-5，-2就是从右往前切，每隔2个输出一个
3.列表的增删改查
#注意点：列表和str是不一样的，list可以发生改变，所以直接就在原来的对象上进行了操作
#例如： lst = ["蒋小鱼","张冲","鲁炎","展大鹏"] lst.append("阿甘") print(lst) #['蒋小鱼', '张冲', '鲁炎', '展大鹏', '阿甘']
#3.1增加
#关键字 #append() 在后面追加 #insert() 指定位置添加 #extend() 迭代添加，也就是一个一个添加
#例子：
lst = ["蒋小鱼","张冲","鲁炎","展大鹏"] lst.append("阿甘") print(lst) #['蒋小鱼', '张冲', '鲁炎', '展大鹏', '阿甘'] lst.insert(2,"项羽") #在鲁炎的位置插入项羽，之前的元素相应的往后移 print(lst) #['蒋小鱼', '张冲', '项羽', '鲁炎', '展大鹏', '阿甘'] #如果使用字符串添加的话那么就是迭代一个一个添加 lst.extend("巴朗") #['蒋小鱼', '张冲', '鲁炎', '展大鹏', '巴', '朗'] #如果使用列表方式添加，那么就是一个元素 lst.extend(["巴朗"]) #['蒋小鱼', '张冲', '鲁炎', '展大鹏', '巴朗'] print(lst) #应用：交互输入员工信息，然后按Q退出，再打印输入的信息出来 # lst=[] # while 1: # content = input("请输入员工的信息,输入Q退出:") # if content.upper() == 'Q': # break # lst.append(content) # print(lst)
#3.2.删除
#pop() #指定位置删除 #remove() #删除元素 #clear() #清空列表 #del() #切片删除
#例子：
lst = ["蒋小鱼","张冲","鲁炎","展大鹏"] lst.pop() #不指定位置，默认删除最后一个 print(lst) #['蒋小鱼', '张冲', '鲁炎'] el = lst.pop(2) #删除2号元素 print(el) #可以查看有没有删除 #鲁炎 print(lst) #再返回列表查看有没有删了 # ['蒋小鱼', '张冲', '展大鹏'] lst.remove("张冲") #指定删除的元素 print(lst) #['蒋小鱼', '鲁炎', '展大鹏'] lst.remove("张三") #如果删除不存在的元素就会报错 print(lst) #报错 lst.clear() #清空 print(lst) del lst[1:3] #切片删除，因为顾头不顾尾所以删除1和2 print(lst) #['蒋小鱼', '展大鹏']
#3.3.修改
# 1、索引修改 # 2、切片修改
#例子：
lst = ["蒋小鱼","张冲","鲁炎","展大鹏","黑脸"] lst[1] = "乌云" #将1号元素修改成乌云，也就是张冲改成乌云 print(lst) #['蒋小鱼', '乌云', '鲁炎', '展大鹏'] #切片：要注意后面的步长和元素的个数如果不对应的话就会报错 lst[1:4:3] = ["龙大队"] print(lst) #['蒋小鱼', '龙大队', '鲁炎', '展大鹏', '黑脸'] # lst[1:4:3] = ["龙大队","张三"] #这样就会报错，因为步长是3，上面只能切到一个，但是修改了两个，不对应，所以就会报错 # print(lst) lst[1:4] = ["大佬"] #将下标1-3替换成大佬 #如果切片没有步长或者步长是1，则不用关心个数 print(lst) #['蒋小鱼', '大佬', '黑脸']
#3.4.查询
#列表是一个可迭代对象，所以可以进行for循环 lst = ["张三","李四","王五","李六"] for el in lst: print(el)
4.列表的嵌套
#嵌套就是一层套着一层，列表套着列表
#采用降维操作，一层一层的看， #就像洋葱一样，一层一层的拨开你的心
#例子：
lst = [1,"张三","蒋小鱼",["鲁炎","张冲",3,["黑脸","龙大队","xiaotian",4],],"乌云"] #找到张冲 print(lst[3][1]) #张冲 #是按照从下标0开始找，3首先是找到第二个列表，然后再在第二个列表里面找到1张冲 #找到黑脸和龙大队 print(lst[3][3][0:2]) #['黑脸', '龙大队'] #也是按照一层一层的找，记住是顾头不顾尾的 #将xiaotian拿到，然后首字母大写，再扔回去 s = lst[3][3][2] s = s.capitalize() lst[3][3][2] = s print(lst) #[1, '张三', '蒋小鱼', ['鲁炎', '张冲', 3, ['黑脸', '龙大队', 'Xiaotian', 4]], '乌云'] #简写 # lst[3][3][2] = lst[3][3][2].capitalize() # print(lst) #将蒋小鱼替换成参谋长 s = lst[2] s = s.replace("蒋小鱼","参谋长") lst[2] = s print(lst) #[1, '张三', '参谋长', ['鲁炎', '张冲', 3, ['黑脸', '龙大队', 'Xiaotian', 4]], '乌云'] #简写 # lst[2] = lst[2].replace("蒋小鱼","参谋长") # print(lst)
5.列表的相关操作
#count() #查询出现的次数 #sort() #排序，默认升序 #len() #列表的长度
#例子：
lst = ["蒋小鱼","张冲","鲁炎","展大鹏","黑脸","蒋小鱼"] c = lst.count("蒋小鱼") #查询蒋小鱼出现的次数 print(c) #2 lst.reverse() #反向打印 print(lst) #['蒋小鱼', '黑脸', '展大鹏', '鲁炎', '张冲', '蒋小鱼'] l = len(lst) #计算列表的长度 print(l) #6 #排序,默认升序 lst = [1,2,3,44,11] lst.sort() print(lst) #[1, 2, 3, 11, 44] #降序 lst = [1,2,3,44,11] lst.sort(reverse=True) print(lst) #[44, 11, 3, 2, 1]
#循环删除的坑点
######循环删除列表中的每一个元素（有坑）#### #方法：1.可以使用clear()清空， # 2.使用另外一种方法，循环删 #首先来个坑，删不掉的 lst = [11,22,33,44,55] for e in lst: lst.remove(e) print(lst) #[22, 44] #直接使用remove是删除不了的，因为删除的时候内部的索引在改变 # 当index=0的时候删除0的字符，当index=1的时候就向下移动了一位，但是列表里面的元素已经往前移填充了 # 所以当删除11，22就变成了第0个索引，当下次删除的时候就是删除第一个索引33，然后就漏掉了22，后面同样 #方法 #1.首先需要记录删除的东西 #2.然后循环要删除的列表，删除真正的列表 #例子：删除性张的 lst = ["张冲","张国荣","张曼玉","蒋小鱼"] zhangs = [] #首先记录性张 for el in lst: zhangs.append(el) #将之前的列表追加到zhangs里面 for e in zhangs: lst.remove(e) #再删除原列表 print(lst) #[] print(zhangs) #['张冲', '张国荣', '张曼玉', '蒋小鱼']