Pandas DataFrame: asof() function

Last update on August 19 2022 21:50:33 (UTC/GMT +8 hours)

DataFrame - asof() function

The asof() function is used to get the last row(s) without any NaNs before where.

If there is no good value, NaN is returned for a Series or a Series of NaN values for a DataFrame

Syntax:

DataFrame.asof(self, where, subset=None)

Parameters:

Name	Description	Type/Default Value	Required / Optional
where	Date(s) before which the last row(s) are returned.	date or array-like of dates	Required
subset	For DataFrame, if not None, only use these columns to check for NaNs.	str or array-like of str Default Value: None	Required

Returns: scalar, Series, or DataFrame
The return can be:

scalar : when self is a Series and where is a scalar
Series: when self is a Series and where is an array-like, or when self is a DataFrame and where is a scalar
DataFrame : when self is a DataFrame and where is an array-like

Return scalar, Series, or DataFrame.

Notes:

Dates are assumed to be sorted. Raises if this is not the case.

Example:

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