calc_d4_method: Calculate Day-4 Method
In Kinekenneth48/rdailychange: Daily Change Method for Spatial Data

Description Usage Arguments Value Details Examples

Takes a numeric vector of daily snow changes, as well as a logical vector of possible indices to include in the Day-4 method, and returns the vector of the Day-4 method.

1	calc_d4_method(d4_cands, dx)

`d4_cands`	A logical vector of indices associated with dx. d4_cands(i) is TRUE if and only if dx(i) and dx(i + 3) are positive, and at most one of dx(i + 1) or dx(i + 2) are negative.
`dx`	A numeric vector of daily snow changes.

A numeric vector of the Day-4 method. See details.

An observation of the Day-4 method consists of the sum of four consecutive elements of dx, the first and last of which must be positive, only one negative observation in the middle, and the sum of the four observations must be positive. The d4_cands logical vector is TRUE when the first and fourth observations are positive, and at most one of the second and third observation is negative. At the indices where d4_cands is TRUE, this function sums the dx(i), dx(i + 1), dx(i + 2), and dx(i + 3). If that sum is positive, it is added as a value of the Day-4 method. The function would then falsify d4_cands(i + 1), d4_cands(i + 2), and d4_cands(i + 3) as an index of dx can be used in a sum only once.

dx <- c(1, -3, 3, 1, 2, 3, 1, -7, 2, -1, -2, 3)
d4_cands <- c(TRUE, FALSE, TRUE, TRUE, FALSE,
              TRUE, FALSE, FALSE, TRUE)
rdailychange:::calc_d4_method(d4_cands, dx)