Warn and fix when t_max is not a multiple of t_save

NEWS.md

@@ -275,6 +275,10 @@ the mathematical details.
   resource abundance at positive consumption, the capacity is increased
   slightly with a warning instead of failing early.
 
+- `project()` now warns when `t_max` is not a multiple of `t_save` and ensures
+  that the state at `t_max` is always saved, even if the final save interval is
+  shorter than `t_save`. (#341)
+
 - New function `psi()` returns an `ArraySpeciesBySize` with the population-level
   reproductive proportion.
 

R/project.R

@@ -219,6 +219,14 @@ project.MizerParams <- function(object, effort,
             t_save <- t_max
         }
         times <- seq(t_start, t_start + t_max, by = t_save)
+        t_end <- t_start + t_max
+        if (!isTRUE(all.equal(times[length(times)], t_end))) {
+            warning("`t_max` (", t_max, ") is not a multiple of `t_save` (",
+                    t_save, "). Results will be saved at `t_max` but the ",
+                    "final save interval will be shorter than `t_save`.",
+                    call. = FALSE)
+            times <- c(times, t_end)
+        }
         effort <- validEffortVector(effort, params)
         effort <- t(array(effort,
             dim = c(length(effort), length(times)),
@@ -271,6 +279,14 @@ project.MizerParams <- function(object, effort,
 
             # Generate new time points
             times <- seq(t_start_effort, t_end, by = save_freq)
+            if (t_max_provided &&
+                !isTRUE(all.equal(times[length(times)], t_end))) {
+                warning("`t_max` (", t_max, ") is not a multiple of `t_save` (",
+                        save_freq, "). Results will be saved at `t_max` but the ",
+                        "final save interval will be shorter than `t_save`.",
+                        call. = FALSE)
+                times <- c(times, t_end)
+            }
 
             # Interpolate effort values for the new time points
             gear_names <- dimnames(effort)[[2]]

tests/testthat/test-project.R

@@ -80,6 +80,24 @@ test_that("time dimension is dealt with properly", {
     expect_equal(dimnames(sim@n)$time, c("2019", "2020", "2021"))
 })
 
+test_that("warns and includes t_max when not a multiple of t_save", {
+    # Scalar effort path
+    expect_warning(
+        sim <- project(params, t_max = 10, t_save = 3, effort = 1,
+                       progress_bar = FALSE),
+        "`t_max`.*`t_save`"
+    )
+    t_dims <- as.numeric(dimnames(sim@n)$time)
+    expect_equal(tail(t_dims, 1), 10)
+    expect_equal(t_dims, c(0, 3, 6, 9, 10))
+
+    # No warning when t_max is exactly a multiple of t_save
+    expect_no_warning(
+        project(params, t_max = 9, t_save = 3, effort = 1,
+                progress_bar = FALSE)
+    )
+})
+
 test_that("project method selects consumer time stepper", {
     params_small <- newMultispeciesParams(NS_species_params_gears[12, , drop = FALSE],
                                           info_level = 0)