DOC: .bfill() (#46631)

[kwhkim]

• closes DOC: simply method='bfill'? #46631 (Replace xxxx with the Github issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[MarcoGorelli]

Thanks @kwhkim - wouldn't this be equivalent of df.reindex(df.index[::-1]).ffill().reindex(df.index)?

In [7]: df.reindex(df.index[::-1]).ffill().reindex(df.index)
Out[7]: 
                   A
2013-08-01 -1.571201
2013-08-02  2.061834
2013-08-05 -0.831290
2013-08-06  1.448895
2013-08-07  1.448895
2013-08-08 -0.258116

In [8]: df.bfill()
Out[8]: 
                   A
2013-08-01 -1.571201
2013-08-02  2.061834
2013-08-05 -0.831290
2013-08-06  1.448895
2013-08-07  1.448895
2013-08-08 -0.258116

[kwhkim]

Yes, I just meant that the contents are the same. Would it be better to be df.reindex(df.index[::-1]).ffill().reindex(df.index)? The context is talking about df.reindex(df.index[::-1]).ffill() so I think it might be better to change df.bfill() to df.bfill().reindex(df.index[::-1]) considering the paragraph it's in.

[MarcoGorelli]

I think just put

df.bfill()

without the comment and it'll be fine

cc @jreback , who originally wrote this example

[jreback]

thanks @kwhkim