pandas.Index.asof#

finalIndex.asof(label)[source]#

Return the label from the index, or, if not present, the previous one.

Assuming that the index is sorted, return the passed index label if itis in the index, or return the previous index label if the passed oneis not in the index.

Parameters:

labelobject

The label up to which the method returns the latest index label.

Returns:

object

The passed label if it is in the index. The previous label if thepassed label is not in the sorted index orNaN if there is nosuch label.

See also

Series.asof

Return the latest value in a Series up to the passed index.

merge_asof

Perform an asof merge (similar to left join but it matches on nearest key rather than equal key).

Index.get_loc

Anasof is a thin wrapper aroundget_loc with method=’pad’.

Examples

Index.asof returns the latest index label up to the passed label.

>>>idx=pd.Index(['2013-12-31','2014-01-02','2014-01-03'])>>>idx.asof('2014-01-01')'2013-12-31'

If the label is in the index, the method returns the passed label.

>>>idx.asof('2014-01-02')'2014-01-02'

If all of the labels in the index are later than the passed label,NaN is returned.

>>>idx.asof('1999-01-02')nan

If the index is not sorted, an error is raised.

>>>idx_not_sorted=pd.Index(['2013-12-31','2015-01-02',...'2014-01-03'])>>>idx_not_sorted.asof('2013-12-31')Traceback (most recent call last):ValueError:index must be monotonic increasing or decreasing