Question

我有一个数字列表，我想根据多个元组列表给出的数字范围进行切片。例如，我有一个看起来像的列表：

my_list = [ 5, 8, 3, 0, 0, 1, 3, 4, 8, 13, 0, 0, 0, 0, 21, 34, 25, 91, 61, 0, 0,]

我还有一个元组列表，它们是我想要的值的标记：

my_tups = [(5,9), (14,18)]

如何使用my_tups作为索引仅返回my_list的值？

Answer 1

使用列表理解：

my_list = [ 5, 8, 3, 0, 0, 1, 3, 4, 8, 13, 0, 0, 0, 0, 21, 34, 25, 91, 61, 0, 0,]
my_tups = [(5,9), (14,18)]

new_list = [my_list[i:j] for i,j in my_tups]

发表评论后：

my_list = [ 5, 8, 3, 0, 0, 1, 3, 4, 8, 13, 0, 0, 0, 0, 21, 34, 25, 91, 61, 0, 0]
my_tups = [(5,9), (14,18)]

new_list = [0 for i in my_list] # Create a list filled with zeros

for i,j in my_tups:
    new_list[i:j] = my_list[i:j] # Replace items with items from my_list using the indexes from my_tups

输出：

>>> new_list
[0, 0, 0, 0, 0, 1, 3, 4, 8, 0, 0, 0, 0, 0, 21, 34, 25, 91, 0, 0, 0]

Answer 2

您可以使用内置slice，如下所示

my_list = [5, 8, 3, 0, 0, 1, 3, 4, 8, 13, 0, 0, 0, 0, 21, 34, 25, 91, 61, 0, 0]
my_tups = [(5, 9), (14, 18)]

my_list2 = [my_list[slice(*o)] for o in my_tups]
print(my_list2)

>>> [[1, 3, 4, 8], [21, 34, 25, 91]]

Answer 3

可能性

from itertools import chain

my_iter = chain(*[my_list[start:end] for start, end in my_tups])

[l for l in my_iter]

给出

[1, 3, 4, 8, 21, 34, 25, 91]

Answer 4

如果我正确理解了问题，您希望在范围my_list和5:9中返回14:18中的值。以下代码应该这样做

my_list = [ 5, 8, 3, 0, 0, 1, 3, 4, 8, 13, 0, 0, 0, 0, 21, 34, 25, 91, 61, 0, 0]
my_tups = [(5,9), (14,18)]

def flattens(lists):
    return sum(lists, [])
flatten([my_list[lo:hi] for (lo, hi) in my_tups])
# gives [1, 3, 4, 8, 21, 34, 25, 91]

Answer 5

您还可以将slice与itertools.starmap：

一起使用

from itertools import starmap

my_list = [ 5., 8., 3., 0., 0., 1., 3., 4., 8., 13., 0., 0., 0., 0., 21., 34., 25., 91., 61., 0., 0.]
my_tups = [(5,9), (14,18)]

result = [my_list[slc] for slc in starmap(slice, my_tups)]
# [[1.0, 3.0, 4.0, 8.0], [21.0, 34.0, 25.0, 91.0]]

使用starmap，您可以随意为任意切片添加步参数：

>>> my_tups = [(5,9,2), (14,18)] # step first slice by 2
>>> [my_list[slc] for slc in starmap(slice, my_tups)]
[[1.0, 4.0], [21.0, 34.0, 25.0, 91.0]]

Answer 6

这应该可以解决问题：

for a, b in my_tups:
    print(my_list[a:b])

您可以使用列表执行其他操作，而不是打印。

Answer 7

你可以在列表理解上做这样的事情

slices = [my_list[x:y] for x, y in my_tups if x < len(my_list) and y < len(my_list)]

Python使用多个元组列表切割列表

7 个答案: