Add Area chart helpers

src/shared/charts/areaPlotDataset.ts

@@ -0,0 +1,48 @@
+import { PlotConfig } from '@/types';
+
+/**
+ * Calculate diff over 2 dataset columns and adds it to the end of the dataset
+ * modifies the incomming dataset array inplace!
+ */
+export function calculateDiff(
+  columns: string[],
+  data: Array<number[]>,
+  colFrom: string,
+  colTo: string,
+): number[][] {
+  const fromIdx = columns.indexOf(colFrom);
+  const toIdx = columns.indexOf(colTo);
+  columns.push(`${colFrom}-${colTo}`);
+
+  return data.map((original, idx) => {
+    // Prevent mutation of original data
+    const candle = original.slice();
+    const diff = idx === 0 ? 0 : candle[toIdx] - candle[fromIdx];
+    candle.push(diff);
+    return candle;
+  });
+}
+
+export function getDiffColumns(plotConfig: PlotConfig): string[][] {
+  const result: string[][] = [];
+  if ('main_plot' in plotConfig) {
+    Object.entries(plotConfig.main_plot).forEach(([key, value]) => {
+      if (value.fill_to) {
+        result.push([key, value.fill_to]);
+      }
+    });
+  }
+  if ('subplots' in plotConfig) {
+    Object.entries(plotConfig.subplots).forEach(([_, subplots]) => {
+      Object.entries(subplots).forEach(([key, value]) => {
+        if (value.fill_to) {
+          result.push([key, value.fill_to]);
+        }
+      });
+    });
+  }
+  console.log('getDiffColumns', result);
+  return result;
+}
+
+export default calculateDiff;

src/types/plot.ts

@@ -7,6 +7,7 @@ export enum ChartType {
 export interface IndicatorConfig {
   color?: string;
   type?: ChartType;
+  fill_to?: string;
 }
 
 export interface PlotConfig {