add documentation, unify implementations of path and fit

1 files changed, 25 insertions, 2 deletions

diff --git a/R/predict.sparsestep.R b/R/predict.sparsestep.R
index 5f8898e..8a4be1a 100644
--- a/R/predict.sparsestep.R
+++ b/R/predict.sparsestep.R
@@ -1,4 +1,27 @@
-predict.sparsestep <- function(object, newx)
+#' @title Make predictions from a SparseStep model
+#'
+#' @description Predicts the outcome variable for the SparseStep model for 
+#' each value of lambda supplied to the model.
+#'
+#' @param object Fitted "sparsestep" object
+#' @param newx Matrix of new values for `x` at which predictions are to be made.
+#' 
+#' @return a matrix of numerical predictions of size nobs x nlambda
+#'
+#' @export
+#' @aliases predict
+#'
+#' @examples
+#' x <- matrix(rnorm(100*20), 100, 20)
+#' y <- rnorm(100)
+#' fit <- sparsestep(x, y)
+#' yhat <- predict(fit)
+#'
+predict.sparsestep <- function(obj, newx)
 {
-	NULL
+  yhat <- newx %*% as.matrix(obj$beta)
+  if (obj$intercept) {
+	  yhat <- yhat + rep(1, nrow(yhat)) %*% obj$a0
+  }
+  return(yhat)
 }