Python 如何查找具有特定值的所有元组？

我正在处理一个填充了元组的列表：

tups = [(1, 2, 4.56), (2, 1, 1.23), (1, 3, 2.776), ...]

我想做两个手术

第一个是查找以数字n开头的所有元组，例如：

def starting_with(n, tups):
    '''Find all tuples with tups that are of the form (n, _, _).'''
    # ...

第二个是相反的，找到第二个值为n的所有元组：

---

从某种意义上说，模式匹配依赖于元组列表。如何在Python中实现这一点？

使用列表理解：

>>> tups = [(1, 2, 4.56), (2, 1, 1.23), (1, 3, 2.776)]
>>> [t for t in tups if t[0] == 1] # starting_with 1
[(1, 2, 4.56), (1, 3, 2.776)]
>>> [t for t in tups if t[1] == 3] # (_, 3, _)
[(1, 3, 2.776)]

备选方案：使用与任意数字匹配的对象

---

但我认为第一种方法会更快

>>> tups = [(1, 2, 4.56), (2, 1, 1.23), (1, 3, 2.776)]
>>> [t for t in tups if t[0] == 1] # starting_with 1
[(1, 2, 4.56), (1, 3, 2.776)]
>>> [t for t in tups if t[1] == 3] # (_, 3, _)
[(1, 3, 2.776)]

>>> class AnyNumber(object):
...     def __eq__(self, other):
...         return True
...     def __ne__(self, other):
...         return False
... 
>>> ANY = AnyNumber()
>>> ANY == 0
True
>>> ANY == 1
True

>>> tups = [(1, 2, 4.56), (2, 1, 1.23), (1, 3, 2.776)]
>>> [t for t in tups if t == (1, ANY, ANY)] 
[(1, 2, 4.56), (1, 3, 2.776)]
>>> [t for t in tups if t == (ANY, 1, ANY)] 
[(2, 1, 1.23)]

def starting_with(n, tups):
    '''Find all tuples with tups that are of the form (n, _, _).'''
    return [t for t in tups if t[0] == n]