用 Python 中最接近的非 NaN 列值填充 NaN

Question

I want to fill e column's NaN with its most closest (by position from left side) not NaN columns' values.

   a    b    c    d    e
0  1  2.0  3.0  6.0  3.0
1  3  5.0  7.0  NaN  NaN
2  2  4.0  NaN  NaN  NaN
3  5  6.0  NaN  NaN  NaN
4  3  NaN  NaN  NaN  NaN

For example, for the second row of e , its most closest Not NaN column is e by position, then we take 7.0 , is it possible to do this in Pandas? Thanks.

The expected output is like this:

   a    b    c    d    e
0  1  2.0  3.0  6.0  3.0
1  3  5.0  7.0  NaN  7.0
2  2  4.0  NaN  NaN  4.0
3  5  6.0  NaN  NaN  6.0
4  3  NaN  NaN  NaN  3.0

Answer 1

如果答案应该是简化获取从左侧到最后一列的所有第一个非缺失值，使用向前填充它们并按位置选择最后一列：

df.e = df.ffill(axis=1).iloc[:, -1]