From 614ae1d37ce45987f24c52ee8bc41ab1790944f9 Mon Sep 17 00:00:00 2001
From: Rich FitzJohn <r.fitzjohn@imperial.ac.uk>
Date: Wed, 18 Sep 2024 09:25:20 +0100
Subject: [PATCH] Add additional example for packer

---
 R/packer.R          | 15 +++++++++++++++
 man/monty_packer.Rd | 15 +++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/R/packer.R b/R/packer.R
index caaaafb6..6f1deed2 100644
--- a/R/packer.R
+++ b/R/packer.R
@@ -196,6 +196,21 @@
 ##'   fixed = list(d = data.frame(n = 1:3, m = runif(3))))
 ##' p$unpack(1:2)
 ##' p$pack(p$unpack(1:2))
+##'
+##' # The example from above, where we create a symmetric 2 x 2 matrix
+##' # from a 3-element vector, alongside a scalar:
+##' p <- monty_packer(
+##'   scalar = "a",
+##'   array = list(b_flat = 3),
+##'   process = function(p) list(b = matrix(p$b_flat[c(1, 2, 2, 3)], 2, 2)))
+##'
+##' # Unpacking we see "b_flat" is still in the list, but "b" is our
+##' # symmetric matrix:
+##' p$unpack(1:4)
+##'
+##' # The processed elements are ignored on the return pack:
+##' p$pack(list(a = 1, b_flat = 2:4, b = matrix(c(2, 3, 3, 4), 2, 2)))
+##' p$pack(list(a = 1, b_flat = 2:4))
 monty_packer <- function(scalar = NULL, array = NULL, fixed = NULL,
                          process = NULL) {
   call <- environment()
diff --git a/man/monty_packer.Rd b/man/monty_packer.Rd
index 09302e9a..48b5fcd2 100644
--- a/man/monty_packer.Rd
+++ b/man/monty_packer.Rd
@@ -199,4 +199,19 @@ p <- monty_packer(
   fixed = list(d = data.frame(n = 1:3, m = runif(3))))
 p$unpack(1:2)
 p$pack(p$unpack(1:2))
+
+# The example from above, where we create a symmetric 2 x 2 matrix
+# from a 3-element vector, alongside a scalar:
+p <- monty_packer(
+  scalar = "a",
+  array = list(b_flat = 3),
+  process = function(p) list(b = matrix(p$b_flat[c(1, 2, 2, 3)], 2, 2)))
+
+# Unpacking we see "b_flat" is still in the list, but "b" is our
+# symmetric matrix:
+p$unpack(1:4)
+
+# The processed elements are ignored on the return pack:
+p$pack(list(a = 1, b_flat = 2:4, b = matrix(c(2, 3, 3, 4), 2, 2)))
+p$pack(list(a = 1, b_flat = 2:4))
 }