创建具有两个不同数字的列表

Question

我有两个号码 x 和 y。 x 例如是 1.5，y 是 1.5 我需要创建一个包含 8 个不同值的列表。

[[0.5,0.5],[0.5,1.5],[0.5,2.5],
[1.5,0.5],[1.5,1.5],[1.5,2.5],
[2.5,0.5],[2.5,1.5],[2.5,2.5]]

[1.5,1.5] #needs to be removed from the above list.

如何在 python 3 中使用不同的 x 和 y 值执行此操作？ x 和 y 将始终是 1 到 10 之间的数字。但它们将是 1.5 或 2.5 或 3.5 等。

Answer 1

试试这个：

values = [0.5, 1.5, 2.5]
[[x, y] for x in values for y in values if x <> y]

输出：

[[0.5, 1.5], [0.5, 2.5], [1.5, 0.5], [1.5, 2.5], [2.5, 0.5], [2.5, 1.5]]

Answer 2

查看this question。

从列表中删除：

list_to_remove = [x, y]
list_of_lists = [[0.5,0.5],[0.5,1.5],[0.5,2.5],
                [1.5,0.5],[1.5,1.5],[1.5,2.5],
                [2.5,0.5],[2.5,1.5],[2.5,2.5]]
list_of_lists.remove(list_to_remove)

请记住，如果list_to_remove 不在list_of_lists 中，这将引发异常。要抓住这一点，您需要：

list_to_remove = [x, y]
list_of_lists = [[0.5,0.5],[0.5,1.5],[0.5,2.5],
                [1.5,0.5],[1.5,1.5],[1.5,2.5],
                [2.5,0.5],[2.5,1.5],[2.5,2.5]]

try:
    list_of_lists.remove(list_to_remove)
except:
    print "{0} is not in list_of_lists".format(str(list_to_remove))

Answer 3

尝试使用以下列表推导：

items = [[a, b] for a in items for b in items if x != a or y != b]

这样：

>>> x = 1.5
>>> y = 1.5
>>> items = [x-1, x, x+1]
>>> items = [[a, b] for a in items for b in items if x != a or y != b]
>>> items 
[[0.5, 0.5], [0.5, 1.5], [0.5, 2.5], [1.5, 0.5], [1.5, 2.5], [2.5, 0.5], [2.5, 1.5], [2.5, 2.5]]
>>> 

编辑：

或者，如果列表理解过于混乱，您可以将其更改为嵌套的for 循环：

for i in items:
    for j in items:
        if i != x or j != y:
            cp.append([i, j])

运行如下：

>>> x = 1.5
>>> y = 1.5
>>> items = [x-1, x, x+1]
>>> cp = []
>>> for i in items:
...     for j in items:
...         if i != x or j != y:
...             cp.append([i, j])
... 
>>> items = cp
>>> items
[[0.5, 0.5], [0.5, 1.5], [0.5, 2.5], [1.5, 0.5], [1.5, 2.5], [2.5, 0.5], [2.5, 1.5], [2.5, 2.5]]
>>>