feat: add xAbsoluteSum method (#245)

Author: jobo322

src/__tests__/__snapshots__/index.test.ts.snap

@@ -9,6 +9,7 @@ exports[`test existence of exported functions 1`] = `
   "getOutputArray",
   "xAbsolute",
   "xAbsoluteMedian",
+  "xAbsoluteSum",
   "xAdd",
   "xApplyFunctionStr",
   "xAutoCorrelation",

src/x/__tests__/xAbsoluteSum.test.ts

@@ -0,0 +1,21 @@
+import { expect, test } from 'vitest';
+
+import { xAbsoluteSum } from '../index';
+
+test('normal array', () => {
+  const array = [-1, 2, -3, 4];
+  expect(xAbsoluteSum(array)).toStrictEqual(10);
+});
+
+test('typed array', () => {
+  const array = new Float64Array([-1, 2, -3, 4]);
+  expect(xAbsoluteSum(array)).toBe(10);
+});
+
+test('typed array from to', () => {
+  const array = new Float64Array([10, -1, 2, -3, 4, 20]);
+
+  const fromIndex = 1;
+  const toIndex = 4;
+  expect(xAbsoluteSum(array, { fromIndex, toIndex })).toBe(10);
+});

src/x/index.ts

@@ -1,6 +1,7 @@
 export * from './getOutputArray';
 export * from './xAbsolute';
 export * from './xAbsoluteMedian';
+export * from './xAbsoluteSum';
 export * from './xAdd';
 export * from './xApplyFunctionStr';
 export * from './xAutoCorrelation';

src/x/xAbsoluteSum.ts

@@ -0,0 +1,23 @@
+import { NumberArray } from 'cheminfo-types';
+
+import { xCheck } from './xCheck';
+import { XGetFromToIndexOptions, xGetFromToIndex } from './xGetFromToIndex';
+
+export function xAbsoluteSum(
+  array: NumberArray,
+  options: XGetFromToIndexOptions = {},
+): number {
+  xCheck(array);
+  const { fromIndex, toIndex } = xGetFromToIndex(array, options);
+
+  let sum = 0;
+  for (let i = fromIndex; i <= toIndex; i++) {
+    if (array[i] < 0) {
+      sum -= array[i];
+    } else {
+      sum += array[i];
+    }
+  }
+
+  return sum;
+}