feat: add xyFilterMinYValue

src/index.ts

@@ -69,6 +69,7 @@ export * from './xy/xyCumulativeDistributionStatistics';
 export * from './xy/xyEnsureGrowingX';
 export * from './xy/xyEquallySpaced';
 export * from './xy/xyExtract';
+export * from './xy/xyFilterMinYValue';
 export * from './xy/xyFilterX';
 export * from './xy/xyFilterXPositive';
 export * from './xy/xyGetNMaxY';

src/xy/__tests__/xyFilterMinYValue.test.ts

@@ -0,0 +1,26 @@
+import { xyFilterMinYValue } from '../xyFilterMinYValue';
+
+describe('xyFilterMinYValue', () => {
+  const x = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+  const y = [10, 8, 6, 4, 2, 0, 2, 4, 6, 8, 10];
+  it('no threshold', () => {
+    const results = xyFilterMinYValue({ x, y });
+    expect(results).toStrictEqual({ x, y });
+    expect(results.x).toBe(x);
+    expect(results.y).toBe(y);
+  });
+  it('threshold very low', () => {
+    const results = xyFilterMinYValue({ x, y }, 0);
+    expect(results).toStrictEqual({ x, y });
+    expect(results.x).toBe(x);
+    expect(results.y).toBe(y);
+  });
+  it('threshold', () => {
+    const results = xyFilterMinYValue({ x, y }, 0.8);
+    expect(results).toStrictEqual({ x: [0, 1, 9, 10], y: [10, 8, 8, 10] });
+  });
+  it('threshold 1.1', () => {
+    const results = xyFilterMinYValue({ x, y }, 1.1);
+    expect(results).toStrictEqual({ x: [], y: [] });
+  });
+});

src/xy/xyFilterMinYValue.ts

@@ -0,0 +1,33 @@
+import { DataXY } from 'cheminfo-types';
+
+import { xMinMaxValues } from '../..';
+
+/** Filter an array x/y based on various criteria x points are expected to be sorted
+ *
+ * @param data - object containing 2 properties x and y
+ * @param minRelativeYValue - the minimum relative value compare to the Y max value
+ * @return filtered data
+ */
+export function xyFilterMinYValue(data: DataXY, minRelativeYValue?: number) {
+  if (minRelativeYValue === undefined) return data;
+
+  const { x, y } = data;
+
+  const { min, max } = xMinMaxValues(y);
+  const threshold = max * minRelativeYValue;
+  if (min >= threshold) return data;
+
+  const newX: number[] = [];
+  const newY: number[] = [];
+  for (let i = 0; i < x.length; i++) {
+    if (y[i] >= threshold) {
+      newX.push(x[i]);
+      newY.push(y[i]);
+    }
+  }
+
+  return {
+    x: newX,
+    y: newY,
+  };
+}