BUG: assigment of list with boolean mask scrambles values

[jorisvandenbossche]

From gitter (didn't see it reported in an issue):

x = pd.Series([None] * 10)
y = [False] * 3 + [True] * 5 + [False] * 2
x[y] = list(range(5))
x

gives:

0    None
1    None
2    None
3       3
4       4
5       0
6       1
7       2
8    None
9    None
dtype: object

For some reason, the assigned values are not in the correct order.

With an array, it works fine (but I think we support list as well?):

In [4]: x[y] = np.array(list(range(5)))

In [5]: x
Out[5]: 
0    None
1    None
2    None
3       0
4       1
5       2
6       3
7       4
8    None
9    None
dtype: object

Tested on pandas master, and also on pandas 0.25 it is buggy (eg in pandas 0.18 it worked fine).

[TomAugspurger]

I thought we had an issue for this, but am not finding it right now. Perhaps I'm remembering the gitter conversation.

[jorisvandenbossche]

I checked the issues since the gitter discussion, and didn't see one about this (at least not in the open issues)

[jreback]

#30580

loooks similar / same

was already merged

[jorisvandenbossche]

Ah, I should have checked the closed ones as well ;)

Closing as duplicate of #30567