python(2):列表

列表由系系列按特定顺序排列的元素组成。可以包含字母表中所有字母，数字或所有家庭成员姓名，也可以添加任何东西，其中的元素之间可以没有任何关系
通常用[]表示列表，用逗号分隔其中的元素

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
print(bicycles)
['trck', 'cannodale', 'redline', 'redline', 'specialized']

1.访问列表元素，只需将元素的位置或索引告诉python即可，索引从0而不是1开始

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
print(bicycles[0])
print(bicycles[1])
print(bicycles[2])
print(bicycles[3])
print(bicycles[4])
trck
cannodale
redline
redline
specialized

2.使用列表中的各个值

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
message = "my first bicycle was a " + bicycles[0].title() + "."
print(message)
my first bicycle was a Trck.

3.修改，添加和删除元素

修改

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles[0] = 'ducati'
print(bicycles)
['ducati', 'cannodale', 'redline', 'redline', 'specialized']

添加，列表末尾添加，append()

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles.append('honda')
print(bicycles)
['ducati', 'cannodale', 'redline', 'redline', 'specialized', 'honda']
#也可以创建一个空列表，再使用一系列append()语句添加元素
bicycles = []
bicycles.append('ducati')
bicycles.append('cannodale')
bicycles.append('redline')
print(bicycles)
['ducati', 'cannodale', 'redline']

在列表中插入元素：insert(),可添加到任何位置

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles.insert(0, 'ducati')
print(bicycles)
['ducati', 'trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles.insert(2, 'ducati')
print(bicycles)
['trck', 'cannodale', 'ducati', 'redline', 'redline', 'specialized']

删除，del,pop()

#del删除
bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
del bicycles[2]
print(bicycles)
['trck', 'cannodale', 'redline', 'specialized']
#删除，pop(),与del区分方法，如果要从列表中删除一个元素并且不在使用它，用del,如果在删除后还能继续使用，用pop
bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
popped_bicycles = bicycles.pop(2)
print(bicycles)
print(popped_bicycles)
['trck', 'cannodale', 'redline', 'specialized']
redline
#根据值删除元素，remove()
bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles.remove('redline')
print(bicycles)
['trck', 'cannodale', 'redline', 'specialized']

4.组织列表

使用sort()对列表进行永久性排序，这里是按字母进行排序

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles.sort()
print(bicycles)
['cannodale', 'redline', 'redline', 'specialized', 'trck']
#按与字母顺序相反的顺序排列列表元素
bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles.sort(reverse=True)
print(bicycles)
['trck', 'specialized', 'redline', 'redline', 'cannodale']

使用sorted()对列表进行临时排序，这里是按字母进行排序

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']

print(sorted(bicycles))
#加reverse=True逆序
bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']

print(sorted(bicycles, reverse=True))
['trck', 'specialized', 'redline', 'redline', 'cannodale']

5.倒着打印列表：反转列表元素的排列顺序,reverse()函数，永久性修改列表元素的排列顺序

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
bicycles.reverse()
print(bicycles)
['specialized', 'redline', 'redline', 'cannodale', 'trck']

6.确定列表的长度：len()

bicycles = ['trck', 'cannodale', 'redline', 'redline', 'specialized']
len(bicycles)
5