fix(radar): Correct display of indexed axis

Typecast axis text value to be dispalyed from the helper function.

Fix #997

Author: netil

spec/shape/shape.radar-spec.js

@@ -190,4 +190,23 @@ describe("SHAPE RADAR", () => {
 			});
 		});
 	});
+
+	describe("Axis", () => {
+		before(() => {
+			args = {
+				data: {
+					columns: [
+						["data1", 330, 350, 220, 400, 150, 330, 230, 390, 95, 195, 220]
+					],
+					type: "radar"
+				}
+			};
+		});
+
+		it("check if default indexed axis text are showing", () => {
+			chart.$.main.selectAll(`.${CLASS.chartRadars} .${CLASS.axis} text`).each(function(d, i) {
+				expect(+this.textContent).to.be.equal(i);
+			});
+		});
+	});
 });

src/shape/radar.js

@@ -259,7 +259,7 @@ extend(ChartInternal.prototype, {
 				.attr("dy", ".5em")
 				.call(selection => {
 					selection.each(function(d) {
-						setTextValue(d3Select(this), d, [-1.2, 1.2], true);
+						setTextValue(d3Select(this), String(d), [-1.2, 1.2], true);
 					});
 				})
 				.datum((d, i) => ({index: i}))