python - 如果每个元组中的第二项是重复项，如何从元组列表中删除元素？

Question

如果每个元组中的第二项是重复项，如何从元组列表中删除元素？

例如，我有一个按第一个元素排序的列表，如下所示：

alist = [(0.7897897,'this is a foo bar sentence'),
(0.653234, 'this is a foo bar sentence'),
(0.353234, 'this is a foo bar sentence'),
(0.325345, 'this is not really a foo bar'),
(0.323234, 'this is a foo bar sentence'),]

期望的输出离开具有最高第一项的元组，应该是：

alist = [(0.7897897,'this is a foo bar sentence'),
(0.325345, 'this is not really a foo bar')]

Answer 1

如果您alist已经按第一个元素从高到低排序：

alist = [(0.7897897,'this is a foo bar sentence'),
(0.653234, 'this is a foo bar sentence'),
(0.353234, 'this is a foo bar sentence'),
(0.325345, 'this is not really a foo bar'),
(0.323234, 'this is a foo bar sentence'),]

seen = set()
out = []
for a,b in alist:
    if b not in seen:
        out.append((a,b))
        seen.add(b)

out就是现在：

[(0.7897897, 'this is a foo bar sentence'),
 (0.325345, 'this is not really a foo bar')]