R/tri.R

In cwhmisc: Miscellaneous Functions for Math, Plotting, Printing, Statistics, Strings, and Tools

triplot <- function(a, f, m, symb = 2, grid = FALSE, ...) {
  ta <- paste(substitute(a))
  tf <- paste(substitute(f))
  tm <- paste(substitute(m))
  tot <- 100 / (a + f + m)
  b <- f * tot
  y <- b * 0.878
  x <- m * tot + b / 2
  par(pty = "s")
  oldcol <- par("col")
  plot(x, y, axes = FALSE, xlab = "", ylab = "",
       xlim = c(-10, 110),
       ylim = c(-10, 110), type = "n", ...)
  points(x, y, pch = symb)
  par(col = oldcol)
  .trigrid(grid)
  text(-5, -5, ta)
  text(105, -5, tm)
  text(50, 93, tf)
  par(pty = "m")
  invisible()
}

".trigrid" <- function(grid = FALSE) {
  lines(c(0, 50, 100, 0), c(0, 87.8, 0, 0))   #draw frame
  if (!grid) {
    for (i in 1:4 * 20) {
      lines(c(i, i - 1), c(0, 2 * 0.878))   #side a-c (base)
      lines(c(i, i + 1), c(0, 2 * 0.878))
      T.j <- i / 2   #side a-b (left)
      lines(c(T.j, T.j + 2), c(i * 0.878, i * 0.878))
      lines(c(T.j, T.j + 1), c(i * 0.878, (i - 2) * 0.878))
      T.j <- 100 - i / 2   #side b-c (right)
      lines(c(T.j, T.j - 2), c(i * 0.878, i * 0.878))
      lines(c(T.j, T.j - 1), c(i * 0.878, (i - 2) * 0.878))
    }
  } else {
    for (i in 1:4 * 20) {
# draw dotted grid
      lines(c(i, i / 2), c(0, i * 0.878), lty = 4, col = 3)   #
      lines(c(i, (50 + i / 2)), c(0, 0.878 * (100 - i)), lty = 4,
          col = 3)   # /
      lines(c(i / 2, (100 - i / 2)), c(i * 0.878, i * 0.878), lty
           = 4, col = 3)   # -
    }
    par(lty = 1, col = 1)
  }
}