feat: add OBV and fix RSI (#31)

@libs/index.ts

@@ -36,6 +36,7 @@ export * from "./indicators/MACD";
 export * from "./indicators/MAX";
 export * from "./indicators/MIN";
 export * from "./indicators/NVI";
+export * from "./indicators/OBV";
 export * from "./indicators/PROD";
 export * from "./indicators/RANGE";
 export * from "./indicators/RANK";

@libs/indicators/OBV.ts

@@ -0,0 +1,24 @@
+import { useEMA, useSeriesMap } from "@libs";
+
+/**
+ * On Balance Volume
+ * @param source - Source Price
+ * @param volume - Volume
+ */
+export const useOBV = (source: Series, volume: Series) => {
+  return useSeriesMap(
+    `OBV(${source.name})`,
+    source,
+    { display: "line", chart: "new" },
+    (i, obv) => {
+      if (i === 0) return 0;
+      if (source[i] > source[i - 1]) {
+        return obv[i - 1] + volume[i];
+      }
+      if (source[i] < source[i - 1]) {
+        return obv[i - 1] - volume[i];
+      }
+      return obv[i - 1];
+    }
+  );
+};

@libs/indicators/RSI.ts

@@ -14,6 +14,10 @@ export const useRSI = (source: Series, period = 14) => {
   );
   const EMA_U = useEMA(U, period);
   const EMA_D = useEMA(D, period);
+  useEffect(() => {
+    EMA_U.tags.display = "none";
+    EMA_D.tags.display = "none";
+  }, []);
   const RSI = useSeriesMap(
     `RSI(${source.name},${period})`,
     source,