请解释一下这是什么意思？

Question

a = [ 'blue' ,  'green' ,  'orange' ,  'purple' ,  'yellow' ] 
b = [3, 2, 5, 4, 1] 
sortedList = [val  for  (_, val)  in  sorted(zip (b, a), key=lambda x: x[0])]
print(sortedList)

Answer 1

>>> zip (b, a) #zip()函数把两个列表转化成可迭代的zip对象
<zip object at 0x0000000002FBD680>
>>> list(zip(b,a))  
[(3, 'blue'), (2, 'green'), (5, 'orange'), (4, 'purple'), (1, 'yellow')]
>>> set(zip(b,a))
{(5, 'orange'), (1, 'yellow'), (3, 'blue'), (2, 'green'), (4, 'purple')}
>>> dict(zip(b,a))  #zip对象可以转化成字典、列表、集合等都可以
{3: 'blue', 2: 'green', 5: 'orange', 4: 'purple', 1: 'yellow'}
>>> list(zip(b,a))
[(3, 'blue'), (2, 'green'), (5, 'orange'), (4, 'purple'), (1, 'yellow')]

>>> sorted(zip (b, a), key=lambda x: x[0]) #sorted()给zip排序，x:x[0]表示以第1列元素3,2,5,4,1来排序；如x:x[1]则排第2列元素，那些“颜色”
[(1, 'yellow'), (2, 'green'), (3, 'blue'), (4, 'purple'), (5, 'orange')]
>>> [val  for  (_, val)  in  sorted(zip (b, a), key=lambda x: x[0])]  # 列表推导式，其中(_, val) 用下划线的那一列元素忽略 
['yellow', 'green', 'blue', 'purple', 'orange']
>>> [val  for  (val,_)  in  sorted(zip (b, a), key=lambda x: x[0])]  # 用(val,_) 则忽略后一列元素
[1, 2, 3, 4, 5]
>>>