                 data: [0]
                    }])
                };

                function renderProvinceName(param, api) {
                    var currentSeriesIndices = api.currentSeriesIndices();
                    currentSeriesIndices.pop(); // remove custom series;

                    var barLayout = api.barLayout({
                        count: currentSeriesIndices.length
                    });

                    var nameTexts = echarts.util.map(currentSeriesIndices, function (serIdx, index