epsShift numeric values in a data frame by an amount eps
shift_values(df, h, i, FUN = `+`, focal = NULL)a data frame or tibble.
numeric; the amount to shift values in df by.
logical; a vector indexing columns of df that should not be
included in the shift.
function; a function to applut the shift. Typically + or -.
character; the focal variable when computing partial
derivatives. This allows shifting only the focal variable by eps.