基本上我在python‘example’中有一个矩阵(尽管要大得多)。我需要用一些python代码来生成数组"example_what_I_want"。我想for循环是可以的,但我该怎么做呢?
example=
[1,2,3,4,5],
[6,7,8,9,10],
[11,12,13,14,15],
[16,17,18,19,20],
[21,22,23,24,25]
example_what_I_want =
[25,24,23,22,21],
[16,17,18,19,20],
[15,14,13,12,11],
[6,7,8,9,10],
[5,4,3,2,1]
所以它以蛇的方式递增。第一排必须倒过来!然后按照这个模式。
谢谢!
我假设example
实际上是:
example = [[1,2,3,4,5],
[6,7,8,9,10],
[11,12,13,14,15],
[16,17,18,19,20],
[21,22,23,24,25]]
在这种情况下,你可以做:
swapped_example = [sublst if idx%2 else sublst[::-1] for
idx,sublst in enumerate(example)][::-1]
这将给你:
In [5]: swapped_example
Out[5]:
[[25, 24, 23, 22, 21],
[16, 17, 18, 19, 20],
[15, 14, 13, 12, 11],
[6, 7, 8, 9, 10],
[5, 4, 3, 2, 1]]
或者,您可以使用iter。
a = [[1,2,3,4,5],
[6,7,8,9,10],
[11,12,13,14,15],
[16,17,18,19,20],
[21,22,23,24,25]]
b = []
rev_a = iter(a[::-1])
while rev_a:
try:
b.append(rev_a.next()[::-1])
b.append(rev_a.next())
except StopIteration:
break
print b
修改(之前不知道。@Adam),
a = iter(a)
while a:
try:
b.insert(0, a.next()[::-1])
b.insert(0, a.next())
except StopIteration:
break
print b[::-1]