Add summary calc to single day

src/Components/SingleDayForecast/Component.tsx

@@ -21,6 +21,28 @@ export class SingleDayForecast extends React.Component<SingleDayForecastProps, {
     this.props = this.props;
   }
 
+  calcSummary(): { avgTemp: number, avgHumidity: number } {
+    let avgTemp: number, avgHumidity: number;
+    {
+      const sumTemp = this.props.forecastCurrentDay.reduce(
+        (prevSum, currentForecast) => {
+          return prevSum + currentForecast.main.temp;
+        },
+        0);
+
+      const sumHumidity = this.props.forecastCurrentDay.reduce(
+        (prevSum, currentForecast) => {
+          return prevSum + currentForecast.main.humidity;
+        },
+        0);
+
+      avgTemp = sumTemp / this.props.forecastCurrentDay.length;
+      avgHumidity = sumHumidity / this.props.forecastCurrentDay.length;
+    }
+
+    return { avgTemp, avgHumidity };
+  }
+
   render() {
     return (
       <div className="SingleDayForecast">