Use a unit root function to determine the minimum number of differences necessary to obtain a stationary time series.

unitroot_ndiffs(x, alpha = 0.05,
unitroot_fn = ~unitroot_kpss(.)["kpss_pvalue"], differences = 0:2,
...)

unitroot_nsdiffs(x, alpha = 0.05, unitroot_fn = ~feat_stl(.,
.period)[2] < 0.64, differences = 0:2, .period = 1, ...)

## Arguments

x A vector to be tested for the unit root. The level of the test. A function (or lambda) that provides a p-value for a unit root test. The possible differences to consider. Additional arguments passed to the unitroot_fn function The period of the seasonality.

## Value

A numeric corresponding to the minimum required differences for stationarity.