Python list排序

print(3/2)  # 此处与C有一定区别，c中两个整数相除结果也是整数
print("type(3/2) " + str(type(3/2))) # type(3/2)<class 'float'>

print(3.0/2)
print("type(3.0/2) " + str(type(3.0/2))) # type(3.0/2) <class 'float'>

print(3%2)  # 求余
print(3**2)  # 9
print(3**3) # 27
print(3**4) # 求3的4次幂 # 81

print(0.1+0.2) # 0.30000000000000004
print("type(0.1+0.2) " + str(type(0.1+0.2))) # type(0.1+0.2) <class 'float'>

print(3*0.1)  # 0.30000000000000004
print("type(3*0.1) " + str(type(3*0.1))) # type(3*0.1) <class 'float'>

bicycles = ['trek','cannondale','redline','specialized']
bicycles[0] = 'ducati' # 更改第一个元素
bicycles.insert(0,'first')
bicycles.insert(-1,'倒数第二个') # 在-1处插入数据，新数据会成为倒数第二个数据
print(bicycles)  # ['first', 'ducati', 'cannondale', 'redline', '倒数第二个', 'specialized']

del bicycles[0]  # 使用del语句（注意，说的是del语句）删除某个元素 # 删除第一个元素
print(bicycles)  

#del bicycles[len(bicycles)] #IndexError: list assignment index out of range

# ['ducati', 'cannondale', 'redline', '倒数第二个', 'specialized']
print(bicycles.pop(1)) # 弹出索引为2的数据： cannondale
print(bicycles.pop(-2)) # 弹出倒数第2个数据："倒数第二个"

print(bicycles) # ['ducati', 'redline', 'specialized']

# 若尝试弹出越界的数据，将报错
# print(bicycles.pop(len(bicycles)))  # IndexError: pop index out of range
# print(bicycles[len(bicycles)]) # IndexError: list index out of range

# 若尝试remove()一个不存在的数据，也会报错
# print(bicycles.remove('honda'))  # ValueError: list.remove(x): x not in list

#print(bicycles.remove('不存在'))# ValueError: list.remove(x): x not in list

bicycles.append('b')
bicycles.append('a')
bicycles.append('c')

bicycles.sort() # ['a', 'b', 'c', 'ducati', 'redline', 'specialized']
print(bicycles) # list的sort()方法，会永久改变数组

#bicycles.sort(True) #TypeError: must use keyword argument for key function
bicycles.sort(reverse = True) # 倒序，使用关键值传参
print(bicycles)