Pandas dataframe.loc : what does "Boolean list with the same length as the row axis" mean?

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Pandas documentation has this Boolean list with the same length as the row axis example, like so:

>>> df = pd.DataFrame([[1, 2], [4, 5], [7, 8]],
...      index=['cobra', 'viper', 'sidewinder'],
...      columns=['max_speed', 'shield'])
>>> df
            max_speed  shield
cobra               1       2
viper               4       5
sidewinder          7       8


>>> df.loc[[False, False, True]]
            max_speed  shield
sidewinder          7       8

Can someone please explain how the df.loc[[False, False, True]] works to get the result shown please?

Thanks.

pandas dataframe python-3.x python
1 Answers

df[[False,False,True]] returns the same as df.loc[[False, False, True]].

df[[False,False,True]] is more intuitive & can be interpreted as: don't return first & second (ie first & second False), return third (ie third is True) row.

In the documentiation, see the bullet point:

  • A boolean array of the same length as the axis being sliced, e.g. [True, False, True].
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