Question

我正在使用以下形式填充的列表：

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

我想执行两项操作。

第一个是查找以 n 编号开头的所有元组，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 n 的所有元组：

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

从某种意义上说，在元组列表上进行模式匹配。我如何在Python中执行此操作？

Answer 1

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)]

ALTERNATIVE ：使用与任意数字匹配的对象。（__eq__）

>>> 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)]

Answer 2

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]

如何找到具有特定值的所有元组？

2 个答案: