Add functions min() and max() to DataArray (#2372)

* fix: DataArray.avg() return type

* feat: Add functions min() and max() to DataArray

docs/docs/api/data-array.md

@@ -116,11 +116,17 @@ export interface DataArray<T> {
     /** Run a lambda on each element in the array. */
     forEach(f: ArrayFunc<T, void>): void;
 
-    /** Calculate the sum of the elements of the array. */
+    /** Calculate the sum of the elements in the array. */
     sum(): number;
 
-    /** Calculate the average of the elements of the array. */
-    avg(): number | undefined;
+    /** Calculate the average of the elements in the array. */
+    avg(): number;
+
+    /** Calculate the minimum of the elements in the array. */
+    min(): number;
+
+    /** Calculate the maximum of the elements in the array. */
+    max(): number;
 
     /** Convert this to a plain javascript array. */
     array(): T[];

src/api/data-array.ts

@@ -115,11 +115,17 @@ export interface DataArray<T> {
     /** Run a lambda on each element in the array. */
     forEach(f: ArrayFunc<T, void>): void;
 
-    /** Calculate the sum of the elements of the array. */
+    /** Calculate the sum of the elements in the array. */
     sum(): number;
 
-    /** Calculate the average of the elements of the array. */
-    avg(): number | undefined;
+    /** Calculate the average of the elements in the array. */
+    avg(): number;
+
+    /** Calculate the minimum of the elements in the array. */
+    min(): number;
+
+    /** Calculate the maximum of the elements in the array. */
+    max(): number;
 
     /** Convert this to a plain javascript array. */
     array(): T[];
@@ -171,7 +177,9 @@ class DataArrayImpl<T> implements DataArray<T> {
         "toString",
         "settings",
         "sum",
-        "avg"
+        "avg",
+        "min",
+        "max",
     ]);
 
     private static ARRAY_PROXY: ProxyHandler<DataArrayImpl<any>> = {
@@ -462,6 +470,14 @@ class DataArrayImpl<T> implements DataArray<T> {
         return this.sum() / this.values.length;
     }
 
+    public min() {
+        return Math.min(...this.values);
+    }
+
+    public max() {
+        return Math.max(...this.values);
+    }
+
     public array(): T[] {
         return ([] as any[]).concat(this.values);
     }

src/test/api/data-array.test.ts

@@ -189,6 +189,16 @@ describe("avg", () => {
     test("numbers", () => expect(da([5, 10, 15]).avg()).toEqual(10));
 });
 
+describe("min", () => {
+    test("empty", () => expect(da([]).min()).toEqual(Infinity));
+    test("numbers", () => expect(da([14, 10, 15]).min()).toEqual(10));
+});
+
+describe("max", () => {
+    test("empty", () => expect(da([]).max()).toEqual(-Infinity));
+    test("numbers", () => expect(da([14, 10, 15]).max()).toEqual(15));
+});
+
 /** Utility function for quickly creating a data array. */
 function da<T>(val: T[]): DataArray<T> {
     return DataArray.wrap(val, DEFAULT_QUERY_SETTINGS);