Add R code for locations example

Author: lumbric

session3_scientific_ecosystem/slides_session3.ipynb

@@ -3408,6 +3408,44 @@
     "ax[0].figure.set_figwidth(12)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {
+    "slideshow": {
+     "slide_type": "slide"
+    }
+   },
+   "source": [
+    "The same thing in R:\n",
+    "\n",
+    "```\n",
+    "set.seed(42)\n",
+    "\n",
+    "canvas_m = 0.3\n",
+    "canvas_r = 900\n",
+    "\n",
+    "locations_n = 25\n",
+    "neighbours_n = 4\n",
+    "\n",
+    "locations = matrix(runif(2*locations_n), ncol=2, \n",
+    "                  dimnames=list(NULL, c('x', 'y')))\n",
+    "\n",
+    "canvas_l = seq(-canvas_m, canvas_m + 1, length=canvas_r)\n",
+    "canvas_c = as.matrix(expand.grid(x = canvas_l, y = canvas_l))\n",
+    "\n",
+    "canvas_c = cbind(canvas_c, v = apply(canvas_c, 1, function(p) {\n",
+    "    d = sqrt((locations[, 1] - p[1])**2 + (locations[, 2] - p[2])**2)\n",
+    "    sum(locations_n**order(d)[1:neighbours_n])\n",
+    "}))\n",
+    "\n",
+    "library(ggplot2)\n",
+    "ggplot(as.data.frame(canvas_c), aes(x = x, y = y)) +\n",
+    "    geom_tile(aes(fill = factor(v))) + \n",
+    "    geom_point(data = as.data.frame(locations), color = 'red') +\n",
+    "    scale_fill_discrete(guide=FALSE)\n",
+    "```"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {