transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)  
transportations[0] = 'train'
print(transportations)  


输出：
['car', 'bicycle', 'motorcycle']
['train', 'bicycle', 'motorcycle']

1.在列表末尾添加元素，append:
transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
transportations.append('train')
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
['car', 'bicycle', 'motorcycle', 'train']

方法：可以先传建一个空列表，再使用一系列函数调用append()来添加元素，例如：

transportations = []
transportations.append('car')
transportations.append('bicycle')
transportations.append('motorcycle')

这种方法很常见，因为经常要等到程序运行后，我们才知道用户要在程序中存储哪些数据。为控制用户，可以首先创建一个空列表，用于存储用户将要输入的值，然后将用户提供的每个新值附加到列表中。

2.在列表中插入元素
在列表中任意位置添加新的元素，insert()：
transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
transportations.insert(1,'train')
print(transportations)


输出：
['car', 'bicycle', 'motorcycle']
['car', 'train', 'bicycle', 'motorcycle']

注意：上述两种方法都是永久修改！！！

1.知道索引下的删除del,例如：
transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
del transportation[1]
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
['car', 'motorcycle']

当我们要将元素从列表中删除，并接着使用它的值，是可以用pop()方法删除列表末尾的的元素，并能够接着使用它。

transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
popped_transportation = transportation.pop()
print(popped_transportation)
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
motorcycle
['car', 'bicycle']

事实上，若我们采用在pop()方法中指定参数的方式，可以删除列表中任意位置的元素，并接着使用。只需要在圆括号中指定要删除的元素索引即可，例如：

transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
popped_transportation = transportations.pop(1)
print(popped_transportation)
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
bicycle
['car', 'motorcycle']

如果我们不知道要删除元素的索引，而知道元素的值，此时我们可以用remove的方法，例如：

transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
transportations.remove('bicycle')
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
['car', 'motorcycle']

   在上例中是采用参数直接传递的方式，当然，也可以通过变量来传递参数，例如：

transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
whatiwanttodelete = 'bicycle'
transportations.remove(whatiwanttodelete)
print(transportations)

也可以达到同样的效果，这样做的好处是我们可以像使用pop()一样，接着使用这个被删除的元素，但需要注意的是，这二者的实现原理是完全不一样的！注意：remove()只能删除第一个指定的值！如果删除的值在列表中出现多次，就需要使用循环来确保将每个值都删除！

1.按照字母顺序排列，例如：
transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
transportations.sort()
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
['bicycle', 'car', 'motorcycle']

2.按照与字母顺序相反的顺序排列元素，只需在使用sort()时传递参数reverse,使reverse = True即可
transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
transportations.sort(reverse = True)
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
['motorcycle', 'car', 'bicycle']

注意：对列表的修改是永久性的！！！

使用方法sorted()对列表临时排序

transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
print(sorted(transportations))
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
['bicycle', 'car', 'motorcycle']
['car', 'bicycle', 'motorcycle']

若要按照与字母顺序相反的顺序排列元素，只需在使用sorted()时传递参数reverse,使reverse = True即可

可见，函数sorted()并没有改变列表元素的原始顺序，如果想通过sorted()永久改变列表，需要将调用sorted()后的列表传递给原始列表，如下：

transportations = sorted(transportations)

注意：在并非所有的值都是小写时，按字母顺序排列列表元素要复杂些。此时在决定排列顺序时，有多种解读大写字母的方式。

倒着打印列表元素reverse()

transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
transportations.reverse()
print(transportations)

输出：
['car', 'bicycle', 'motorcycle']
['motorcycle', 'bicycle', 'car']

注意：reverse()不是按照字母顺序颠倒顺序，而只是将列表元素反转而已！！！如果想要恢复到原来的顺序只需要再次调用reverse即可。

确定列表长度len()

transportations = ['car' , 'bicycle' , 'motorcycle']
print(transportations)
print(len(transportations))

输出：
['car', 'bicycle', 'motorcycle']
3