let NLset() coerce a numeric worldArray layer to character

NEWS.md

@@ -13,7 +13,7 @@
 
 ## Bugfixes
 * `[` on a `worldArray` assumed the array had exactly two layers, so extracting patch values from a `worldArray` with any other number of layers failed with "dims [product 2] do not match the length of object". It now uses the actual number of layers.
-* stacking a `worldMatrix` of character values alongside a numeric one no longer corrupts both layers (#49). An `array` holds a single type, so the character values used to turn every layer into character, and were then coerced back to `NA` on the way out. `worldArray` now stores character layers as integer codes with their categories in a new `levels` slot, exactly as `agentMatrix` already does for character columns. `of()` reports the character values, `plot()` draws the layer as a categorical raster instead of warning "NAs introduced by coercion", `NLwith()` and `NLset()` accept and return the characters, and `[[` and `$` give back a character `worldMatrix`. Numeric layers stacked alongside a character one keep their own type.
+* stacking a `worldMatrix` of character values alongside a numeric one no longer corrupts both layers (#49). An `array` holds a single type, so the character values used to turn every layer into character, and were then coerced back to `NA` on the way out. `worldArray` now stores character layers as integer codes with their categories in a new `levels` slot, exactly as `agentMatrix` already does for character columns. `of()` reports the character values, `plot()` draws the layer as a categorical raster instead of warning "NAs introduced by coercion", `NLwith()` and `NLset()` accept and return the characters, and `[[` and `$` give back a character `worldMatrix`. Numeric layers stacked alongside a character one keep their own type. Assigning character values to a numeric layer with `NLset()` turns that whole layer into a character one, as assigning a string into a numeric vector does in base R, keeping the values of the `patches` that were not assigned.
 * `inRadius()` with `torus = TRUE` no longer reports patches that were not among the `agents2` supplied;
 * `of()` on an `agentMatrix` now returns columns in the order given by `var` when a mix of factor and numeric variables is requested.
 

R/helpers.R

@@ -86,14 +86,19 @@ sampleWithin <- function(group) {
       return(list(world = world, val = asNum))
     }
 
-    if (!allPatches) {
-      stop(
-        "cannot assign character values to only some patches of the numeric ",
-        "worldArray layer '", var, "'.\n",
-        "Assign the whole layer instead, e.g. world[['", var, "']] <- aCharacterWorld."
-      )
+    ## A layer holds one type, so giving a numeric layer genuine character
+    ## values turns the whole layer into a character one, the way assigning a
+    ## string into a numeric vector does in base R. The numbers already in the
+    ## patches that are *not* being assigned become categories in their own
+    ## right, so that they survive rather than being reread as codes.
+    if (allPatches) {
+      lvls <- character(0)
+    } else {
+      existing <- world@.Data[, , var]
+      lvls <- as.character(sort(unique(existing[!is.na(existing)])))
+      world@.Data[, , var] <- match(as.character(existing), lvls)
+      world@levels[[var]] <- lvls
     }
-    lvls <- character(0)
   }
 
   newLvls <- union(lvls, setdiff(unique(as.character(val)), NA_character_))

R/worldNLR-classes-methods.R

@@ -230,6 +230,13 @@ setMethod(
 #' character layer reports the characters, and `[[` and `$` return a character
 #' `worldMatrix`. The codes are visible only in the `.Data` slot itself.
 #'
+#' Because a layer holds a single type, giving a numeric layer character values
+#' with [NLset()] turns that whole layer into a character one, just as assigning
+#' a string into a numeric vector does in base R. The values in the `patches`
+#' that were not assigned are kept, as characters. Values that merely arrive as
+#' strings but are numbers, as they do from `cbind(a = 1, b = "x")`, are left
+#' numeric; pass `val` as a `data.frame` to keep column types distinct.
+#'
 #' @aliases worldArray
 #' @name worldArray-class
 #' @rdname worldArray-class

tests/testthat/test-NetLogoR-classes.R

@@ -188,11 +188,22 @@ test_that("NLwith and NLset work on a character worldArray layer", {
   w4 <- NLset(world = w, agents = cbind(pxcor = 0, pycor = 0), var = "num", val = -99)
   expect_identical(of(world = w4, agents = cbind(pxcor = 0, pycor = 0), var = "num"), -99)
 
-  ## turning only some patches of a numeric layer into characters is rejected
-  expect_error(
-    NLset(world = w, agents = cbind(pxcor = 0, pycor = 0), var = "num", val = "oops"),
-    "only some patches"
-  )
+  ## giving a numeric layer character values turns the whole layer into a
+  ## character one, as assigning a string into a numeric vector does in base R
+  w5 <- NLset(world = w, agents = cbind(pxcor = 0, pycor = 0), var = "num", val = "oops")
+  expect_identical(of(world = w5, agents = cbind(pxcor = 0, pycor = 0), var = "num"), "oops")
+  ## the patches that were not assigned keep their values, as characters
+  expect_identical(of(world = w5, agents = cbind(pxcor = 1, pycor = 1), var = "num"), "17")
+  expect_false(is.character(w5@.Data))
+  ## every original value survived, none were reread as codes
+  expect_setequal(w5@levels$num, c(as.character(1:25), "oops"))
+  ## and the other layer is untouched
+  expect_identical(of(world = w5, agents = cbind(pxcor = 1, pycor = 1), var = "hab"), "land")
+
+  ## numbers that merely arrive as strings are still numbers
+  w6 <- NLset(world = w, agents = cbind(pxcor = 0, pycor = 0), var = "num", val = "42")
+  expect_identical(of(world = w6, agents = cbind(pxcor = 0, pycor = 0), var = "num"), 42)
+  expect_null(w6@levels$num)
 })
 
 test_that("[[<- re-encodes a replaced worldArray layer", {