pandas.api.typing.Rolling.first

Rolling.first(numeric_only=False)

Calculate the rolling First (left-most) element of the window.

Return the first observed value in each rolling window. This is useful for tracking the starting value of a window as it slides forward.

Parameters:

numeric_onlybool, default False

Include only float, int, boolean columns.

Returns:

Series or DataFrame

Return type is the same as the original object with np.float64 dtype.

See also

GroupBy.first

Similar method for GroupBy objects.

Rolling.last

Method to get the last element in each window.

Examples

The example below will show a rolling calculation with a window size of three.

>>> s = pd.Series(range(5))
>>> s.rolling(3).first()
0         NaN
1         NaN
2         0.0
3         1.0
4         2.0
dtype: float64