Question

我正在寻找一种方法来填充列表中的na，其中包含python中的最后一个已知值。

示例：Input a = [1, 2, None, 4, 5, None, 5, 4, None, 7, None, None, None, None]

Output: [1, 2, 2, 4, 5, 5, 5, 4, 4, 7, 7, 7, 7,7]

如果第一个元素是None，那么我们必须用列表中的第一个非null元素替换它，然后执行上面的任务。

Answer 1

只需使用enumerate和next。

a = [1, 2, None, 4, 5, None, 5, 4, None, 7, None, None, None, None]
b = [None, 2, None, 4, 5, None, 5, 4, None, 7, None, None, None, None]
c = [None, None, None, 4, 5, None, 5, 4, None, 7, None, None, None, None]


def fill_none(a):
    for i, j in enumerate(a):
        if j is None:
            if i == 0:
                a[0] = next(item for item in a if item is not None)
            else:
                a[i] = a[i-1]
    return a


>>> print fill_none(a)
[1, 2, 2, 4, 5, 5, 5, 4, 4, 7, 7, 7, 7, 7]
>>> print fill_none(b)
[2, 2, 2, 4, 5, 5, 5, 4, 4, 7, 7, 7, 7, 7]
>>> print fill_none(c)
[4, 4, 4, 4, 5, 5, 5, 4, 4, 7, 7, 7, 7, 7]

Answer 2

试试这个：

lis = [1, 2, None, 4, 5, None, 5, 4, None, 7, None, None, None, None]
for x in range(len(lis)):
    if lis[0] == None:
        lis[0] = 1
    if lis[x] == None:
        lis[x] = lis[x - 1]
print(lis)

输出= [1,2,2,4,5,5,5,4,4,7,7,7,7,7]

使用Python中的最后一个已知值在列表中填充NA

2 个答案: