Pandas Series: last() function

Subsetting final periods of time in Pandas series

The last() function (convenience method ) is used to subset final periods of time series data based on a date offset.

Return a boolean Series showing whether each element in the Series matches an element in the passed sequence of values exactly.

Syntax:

Series.last(self, offset)[source]

Parameters:

Returns: subset - same type as caller

Raises: TypeError
If the index is not a DatetimeIndex

Example:

Python-Pandas Code:

import numpy as np
import pandas as pd
i = pd.date_range('2019-02-09', periods=4, freq='2D')
ts = pd.DataFrame({'X': [1,2,3,4]}, index=i)
ts

Output:

            X
2019-02-09	1
2019-02-11	2
2019-02-13	3
2019-02-15	4

Example - Get the rows for the last 3 days:

Python-Pandas Code:

import numpy as np
import pandas as pd
i = pd.date_range('2019-02-09', periods=4, freq='2D')
ts = pd.DataFrame({'X': [1,2,3,4]}, index=i)
ts.last('3D')

Output:

            X
2019-02-13	3
2019-02-15	4

Note: The data for 3 last calender days were returned, not the last 3 observed days in the dataset, and therefore data for 2019-02-11 was not returned.

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