2.3.2.9000: plot c(0,0,0) at origin

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: Ternary
-Version: 2.3.2
+Version: 2.3.2.9000
 Title: Create Ternary and Holdridge Plots
 Description: Plots ternary diagrams (simplex plots / Gibbs triangles) and
   Holdridge life zone plots <doi:10.1126/science.105.2727.367> using the

NEWS.md

@@ -1,3 +1,6 @@
+# Ternary v2.3.2.9000 (development)
+- Support plotting of `c(0, 0, 0)`, at origin.
+
 # Ternary v2.3.2 (2024-07-25)
 - Document reading data into R in vignette for new users.
 - Provide package anchors in documentation pages.

R/Coordinates.R

@@ -83,13 +83,17 @@ TernaryToXY.numeric <- function(
     c(3, 2, 1),
     c(2, 3, 1)
   )]
+  if (!any(as.logical(abc))) {
+    # abc == c(0, 0, 0)
+    abc <- c(1, 1, 1)
+  }
 
-  x_deviation <- abc[3] / sum(abc)
+  x_deviation <- abc[[3]] / sum(abc)
   if (x_deviation == 1) {
     x <- cos(pi / 6)
     y <- 0
   } else {
-    y_deviation <- (abc[1] - abc[2]) / sum(abc[1:2])
+    y_deviation <- (abc[[1]] - abc[[2]]) / sum(abc[1:2])
     x <- x_deviation * cos(pi / 6)
     y <- y_deviation * (1 - x_deviation) / 2
   }

tests/testthat/test-Coordinates.R

@@ -141,6 +141,10 @@ test_that("OutsidePlot() works", {
   expect_true(OutsidePlot(0, 0.8, tolerance = 0.05))
 })
 
+test_that("Corner cases are correct", {
+  expect_equal(TernaryToXY(c(0, 0, 0)), TernaryToXY(c(2, 2, 2)))
+})
+
 test_that("Errors are handled nicely", {
   expect_error(TernaryCoords(1:3, direction = 5))
   expect_error(TernaryXRange(direction = 5))