python之列表【list】

这里介绍下列表的功能

#切片：列表[a:b]，从下标为a开始，到下标为（b-1）的元素
# name = [0,1,2,3,4,5,6,7,8,9]
# print(name[1:6])
#
# 结果
# [1, 2, 3, 4, 5]

# name = [0,1,2,3,4,5,6,7,8,9]
# print(name[3:])
#
# 结果
# [3, 4, 5, 6, 7, 8, 9]

# name = [0,1,2,3,4,5,6,7,8,9]
# print(name[:4])
#
# 结果
# [0, 1, 2, 3]

#打印下标为等差数列的元素的内容print(变量名[a:b:2])，这个2就为步长
# name = [0,1,2,3,4,5,6,7,8,9]
# print(name[0::2])
#
# 结果
# [0, 2, 4, 6, 8]

#切片还可以不断的切分元素的值
# name = ["CuiYueRong","CuiHongYan",["ZhouYongBo","WangXianZhi"]]
# print(name[2])
# 结果
# ['ZhouYongBo', 'WangXianZhi']
#
# print(name[2][0])
# 结果
# ZhouYongBo
#
# print(name[2][0][2])
# 结果
# o

#=========================================================================================
#修改：列表名[1] = xxxxx
#name = ["CuiYueRong","CuiHongYan",["ZhouYongBo","WangXianZhi"]]
# name[0] = "CuiXiWen"
# print(name)
# 结果
# ['CuiXiWen', 'CuiHongYan', ['ZhouYongBo', 'WangXianZhi']]
#
# name[2][0] = "1234"
# print(name)
# 结果
# ['CuiXiWen', 'CuiHongYan', ['1234', 'WangXianZhi']]

# name[2][0][0] = 'A'
# print(name)
#
# #注意，这里就不能改了

#===========================================================================================
#插入，变量名.insert(a,"xxxxx")，在列表为a的位置插入元素的内容为"xxxxxx",变量名.append"xxxxxxxxxxx"),在列表的最后插入一个元素,也就是追加；
#这里如果是插入到-b的位置，则最终的插入的位置是-b-1的位置

# name = ["CuiYueRong","CuiHongYan",["ZhouYongBo","WangXianZhi"]]
# name.insert(1,"CuiWeiMing")
# print(name)
# 结果
# ['CuiYueRong', 'CuiWeiMing', 'CuiHongYan', ['ZhouYongBo', 'WangXianZhi']]
#
#
# name.append("Cuiqing")
# print(name)
# 结果
# ['CuiYueRong', 'CuiWeiMing', 'CuiHongYan', ['ZhouYongBo', 'WangXianZhi'], 'Cuiqing']

#=============================================================================================
#删除，用remove,变量名.remove("xxxxxx")，这里的xxxxxx不是下标，而是元素的值
# name = ["CuiYueRong","CuiHongYan",["ZhouYongBo","WangXianZhi"]]
# name.remove("CuiYueRong")
# print(name)
# 结果
# ['CuiHongYan', ['ZhouYongBo', 'WangXianZhi']]

#删除，用pop,变量名.pop("xxxxxx")，这里的xxxxxx是下标，不是元素的内容
# name = ["CuiYueRong","CuiHongYan",["ZhouYongBo","WangXianZhi"]]
# name.pop(1)
# print(name)
# 结果
# ['CuiYueRong', ['ZhouYongBo', 'WangXianZhi']]

#删除列表，用del 列表名
# name = ["CuiYueRong","CuiHongYan",["ZhouYongBo","WangXianZhi"]]
# del name
# print(name)

#del也可以删除多个连续的元素 del name[a:b]，删除下标为a的元素到下标为（b-1）的元素
# name = ["CuiYueRong","CuiHongYan",["ZhouYongBo","WangXianZhi"]]
# print(name)
# del name[1:]
# print(name)
#
# 结果
# ['CuiYueRong']

#================================================================================
#获取列表中某个元素的下标，如果列表中有多个这个元素，只会取第一个元素的下标
# num = [1,2,3,4,4,5,3,4]
# print(num.index(1))
# print(num.index(4))
#
# 结果
# 0
# 3

#==================================================================================
#获取某个元素在列表中出现的次数 列表名.count("xxxx")，统计列表中xxxx出现的次数
# num = [1,2,3,4,4,5,3,4]
# print(num.count(4))
#
# 结果
# 3

# num = [1,2,3,4,4,5,3,4]
# print(num.count(0))
# 结果
# 0

#===================================================================================
#检查一个列表中是否存在某个值，用in的方法
# num = [1,2,3,4,4,5,3,4]
# print(2 in num)
# 结果
# True

# num = [1,2,3,4,4,5,3,4]
# print("a" in num)
# 结果
# False
# num = [1,2,3,4,4,5,3,4]
# if "a" in num:
# print("a is in num")
# else:
# print("a is not in num")
#
# num = [1,2,3,4,4,5,3,4]
# if 2 in num:
# print("2 is in num")
# else:
# print("2 is not in num")

#==========================================================================
#copy一个列表，这里在python2.6中需要导入一个模块才能支持，这里需要解释一下
# import copy，这里copy，如果拷贝的list中还有一个列表，则子列表不会拷贝过来，此时如果修改子列表的内容，则该子列表的母列表和新拷贝出来的
#列表的值都会被改变

# num = [0,1,2,3,4,["a","b","c","d"]]
# num1 = copy.copy(num)
# print(num1)
#
# num[5][0] = "A"
# num[0] = "Cuiyuerong"
# print(num,num1)
# 结果
# (['Cuiyuerong', 1, 2, 3, 4, ['A', 'b', 'c', 'd']], [0, 1, 2, 3, 4, ['A', 'b', 'c', 'd']])

# import copy，这里描述一下deepcopy，会把list中的所有列表的内容全部拷贝过来
# num = [0,1,2,3,4,["a","b","c","d"]]
# num2 = copy.deepcopy(num)
# num[5][0] = "A"
# num[0] = "Cuiyuerong"
# print(num,num2)
# 结果
# (['Cuiyuerong', 1, 2, 3, 4, ['A', 'b', 'c', 'd']], [0, 1, 2, 3, 4, ['a', 'b', 'c', 'd']])

#=========================================================================
#用extend把两个列表合在一起
# num1 = [0,1,2,3,4,["a","b","c","d"]]
# num2 = [0,1,2,3,4,["a","b","c","d"]]
# num1.extend(num2)
# print(num1)

#========================================================================
#反转列表：列表名.reverse()
# num1 = [0,1,2,3,4,["a","b","c","d"]]
#
# num1.reverse()
# print(num1)
#
# 结果
# [['a', 'b', 'c', 'd'], 4, 3, 2, 1, 0

#========================================================================
#对列表重新排序，列表名.sort()
# num1 = ["d",1,2,3,0,["a","b","c","d"]]
# num1.sort()
# print(num1)
#
# 结果
# [0, 1, 2, 3, ['a', 'b', 'c', 'd'], 'd']

#===========================================================================
#来一个小练习，如果一个list中有多个相同的元素，现在的需求是把list中的这个元素所有的值都修改为另外的一个值
# num = [1,2,3,4,5,6,1,1,6,77,1,2,45,1,3,1]
# count_of_ele = num.count(1)
# for i in range(count_of_ele):
# index_of_ele = num.index(1)
# num[index_of_ele] = "A"
# print(num.count(1))
# print(num.count("A"))
# print(num)