add example arc_color_mappings

examples/specs/arc_color_mappings.vl.json

@@ -0,0 +1,59 @@
+{
+  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
+  "description": "A simple pie chart with embedded data.",
+  "data": {
+    "values": [
+      {
+        "category": 1,
+        "value": 4
+      },
+      {
+        "category": 2,
+        "value": 6
+      },
+      {
+        "category": 3,
+        "value": 10
+      },
+      {
+        "category": 4,
+        "value": 3
+      },
+      {
+        "category": 5,
+        "value": 7
+      },
+      {
+        "category": 6,
+        "value": 8
+      }
+    ]
+  },
+  "mark": "arc",
+  "encoding": {
+    "theta": {
+      "field": "value",
+      "type": "quantitative"
+    },
+    "color": {
+      "field": "category",
+      "type": "nominal",
+      "scale": {
+        "range": [
+          "purple",
+          "green",
+          "blue",
+          "yellow",
+          "magenta",
+          "brown"
+        ],
+        "domain": {
+          "unionWith": [
+            5,
+            6
+          ]
+        }
+      }
+    }
+  }
+}