有没有办法用相邻值替换列表中的特定值？

Question

我的代码应该将缺失值更改为其有效的直接相邻值。但是，它似乎没有正确运行，我不太确定错误在哪里。

因此必须将缺失值校正为其相邻值的平均值。但是，如果存在连续的缺失值，则应使用有效的相邻值对其进行校正。仅使用基本的 Python 函数，如 for 循环和 if/else。

    data = [1, -999, -999, 3, 4]
    missing = -999
    for i, num in enumerate(data):
        if num == missing:
            if [i-1] and [i+1] != missing:
                data[i] = (data[i-1] + data[i+1]) / 2
            elif [i-1] != missing and [i+1] == missing:
                data[i] = data[i-1]
            elif [i+1] != missing and [i-1] == missing:
                data[i] = data[i+1]
            else:
                data[i] = data[i]
            print(data)

例如：

    data = [1, 2, -999, 4, 5], [1, -999, -999, 3, 4], [-999, -999, 3, 4, 5], [-999, -999, -999, -999, -999]
    expected output = [1, 2, 3, 4, 5], [1, 1, 3, 3, 4], [3, 3, 3, 4, 5], [-999, -999, -999, -999, -999]

Answer 1

试试下面的代码：

data = [1, 2, 3, -999, -999]
missing = -999
for i, num in enumerate(data):
    if (num == missing) and (i not in [0, len(data) - 2, len(data) - 1]):
        if (data[i-1] != missing) and (data[i+1] != missing):
            data[i] = (data[i-1] + data[i+1]) / 2
        elif (data[i-1] != missing) and (data[i+1] == missing):
            data[i] = data[i-1]
            data[i+1] = data[i+2]
        elif (data[i+1] != missing) and (data[i-1] == missing):
            data[i] = data[i+1]
            data[i-1] = data[i-2]
    elif (num == missing) and (i == 0):
        if data[i+1] != missing:
            data[i] = data[i+1]
        else:
            data[i] = data[i+2]
    elif (num == missing) and (i in [len(data) - 2, len(data) - 1]):
        if data[i-1] != missing:
            data[i] = data[i-1]
        else:
            data[i] = data[i-2]
print(data)

输出：

[3, 3.0, 3, 4, 5]