feat(bitfield): add ILength impl, add .density()

- refactor popCount() impls to use fn from @thi.ng/binary pkg

packages/bitfield/src/bitfield.ts

@@ -1,14 +1,15 @@
-import type { Fn2, IClear, ICopy } from "@thi.ng/api";
+import type { Fn2, IClear, ICopy, ILength } from "@thi.ng/api";
 import { align } from "@thi.ng/binary/align";
+import { popCountArray } from "@thi.ng/binary/count";
 import { bitAnd, bitNot, bitOr, bitXor } from "@thi.ng/binary/logic";
 import { assert } from "@thi.ng/errors/assert";
-import { binOp, popCount, toString } from "./util.js";
+import { binOp, toString } from "./util.js";
 
 /**
  * 1D bit field, backed by a Uint32Array. Hence size is always rounded
  * up to a multiple of 32.
  */
-export class BitField implements IClear, ICopy<BitField> {
+export class BitField implements IClear, ICopy<BitField>, ILength {
     data: Uint32Array;
     n: number;
 
@@ -19,6 +20,10 @@ export class BitField implements IClear, ICopy<BitField> {
         !isNumber && this.setRange(0, <any>bits);
     }
 
+    get length() {
+        return this.n;
+    }
+
     /**
      * Yields iterator of the field's individual bits.
      */
@@ -135,7 +140,14 @@ export class BitField implements IClear, ICopy<BitField> {
      * Returns number of set bits (1's) in the bitfield.
      */
     popCount() {
-        return popCount(this.data);
+        return popCountArray(this.data);
+    }
+
+    /**
+     * Same as {@link BitField.popCount}, but as normalized ratio/percentage.
+     */
+    density() {
+        return this.popCount() / this.n;
     }
 
     and(field: BitField) {

packages/bitfield/src/bitmatrix.ts

@@ -1,10 +1,11 @@
 import type { Fn2, IClear, ICopy } from "@thi.ng/api";
 import { align } from "@thi.ng/binary/align";
+import { popCountArray } from "@thi.ng/binary/count";
 import { bitAnd, bitNot, bitOr, bitXor } from "@thi.ng/binary/logic";
 import { assert } from "@thi.ng/errors/assert";
 import { ensureIndex } from "@thi.ng/errors/out-of-bounds";
 import { BitField } from "./bitfield.js";
-import { binOp, popCount, toString } from "./util.js";
+import { binOp, toString } from "./util.js";
 
 /**
  * MxN row-major 2D bit matrix, backed by a Uint32Array. Hence the width
@@ -23,6 +24,10 @@ export class BitMatrix implements IClear, ICopy<BitMatrix> {
         this.data = new Uint32Array(rows * this.stride);
     }
 
+    get length() {
+        return this.m * this.n;
+    }
+
     clear() {
         this.data.fill(0);
     }
@@ -128,10 +133,17 @@ export class BitMatrix implements IClear, ICopy<BitMatrix> {
         return this.binOp(this, bitNot);
     }
 
+    /**
+     * Returns number of set bits (1's) in the matrix.
+     */
+    popCount() {
+        return popCountArray(this.data);
+    }
+
     popCountRow(m: number) {
         ensureIndex(m, 0, this.m);
         m *= this.stride;
-        return popCount(this.data.subarray(m, m + this.stride));
+        return popCountArray(this.data.subarray(m, m + this.stride));
     }
 
     popCountColumn(n: number) {
@@ -145,6 +157,13 @@ export class BitMatrix implements IClear, ICopy<BitMatrix> {
         return res;
     }
 
+    /**
+     * Same as {@link BitMatrix.popCount}, but as normalized ratio/percentage.
+     */
+    density() {
+        return this.popCount() / this.length;
+    }
+
     row(m: number) {
         ensureIndex(m, 0, this.m);
         const row = new BitField(this.n);

packages/bitfield/src/util.ts

@@ -1,6 +1,5 @@
 // thing:no-export
 import type { Fn2 } from "@thi.ng/api";
-import { popCount as $popCount } from "@thi.ng/binary/count";
 import { B32 } from "@thi.ng/strings/radix";
 
 /**
@@ -26,21 +25,3 @@ export const binOp = (
 ) => {
     for (let i = src.length; i-- > 0; ) dest[i] = op(src[i], dest[i]);
 };
-
-/**
- * Returns number of set bits (1's) in the given array (index range).
- *
- * @param data - 
- * @param i - 
- * @param n - 
- *
- * @internal
- **/
-export const popCount = (data: Uint32Array, i = 0, n = data.length) => {
-    let num = 0;
-    for (let m = i + n; i < m; i++) {
-        const x = data[i];
-        x > 0 && (num += $popCount(x));
-    }
-    return num;
-};