Barebone function for PLNfit initialization (useful for variance_jack…

…knife and variance_bootsrap)

R/utils.R

@@ -252,3 +252,14 @@ create_parameters <- function(
        Sigma  = sigma * toeplitz(x = rho^seq(0, p-1)),
        depths = depths)
 }
+
+#' barebone function to compute starting points for B and M
+#' @importFrom stats lm.fit
+starting_point <- function(Y, X, O, w) {
+  # Y = responses, X = covariates, O = offsets, w = weights
+  n <- nrow(Y); p <- ncol(Y); d <- ncol(X)
+  fits <- lm.fit(w * X, w * log((1 + Y)/exp(O)))
+  list(B = matrix(fits$coefficients, d, p),
+       M = matrix(fits$residuals, n, p),
+       S = matrix(.1, n, p))
+}