feat: Add columnArray array constructor argument.

docs/api/table.md

@@ -217,11 +217,12 @@ dt.columnAt(1).get(1) // 5
 ```
 
 <hr/><a id="columnArray" href="#columnArray">#</a>
-<em>table</em>.<b>columnArray</b>(<i>name</i>) · [Source](https://github.com/uwdata/arquero/blob/master/src/table/column-table.js)
+<em>table</em>.<b>columnArray</b>(<i>name</i>[, <i>arrayConstructor</i>]) · [Source](https://github.com/uwdata/arquero/blob/master/src/table/column-table.js)
 
-Get an array of values contained in the column with the given *name*. Unlike direct access through the table [column](#column) method, the array returned by this method respects any table filter or orderby criteria.
+Get an array of values contained in the column with the given *name*. Unlike direct access through the table [column](#column) method, the array returned by this method respects any table filter or orderby criteria. By default, a standard [Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array) is returned; use the *arrayConstructor* argument to specify a [typed array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray).
 
 * *name*: The column name.
+* *arrayConstructor*: An optional array constructor (default [`Array`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Array)) to use to instantiate the output array. Note that errors or truncated values may occur when assigning to a typed array with an incompatible type.
 
 *Examples*
 
@@ -236,6 +237,11 @@ aq.table({ a: [1, 2, 3], b: [4, 5, 6] })
   .columnArray('b'); // [ 5, 6 ]
 ```
 
+```js
+aq.table({ a: [1, 2, 3], b: [4, 5, 6] })
+  .columnArray('b', Int32Array); // Int32Array.of(4, 5, 6)
+```
+
 <hr/><a id="columnIndex" href="#columnIndex">#</a>
 <em>table</em>.<b>columnIndex</b>(<i>name</i>) · [Source](https://github.com/uwdata/arquero/blob/master/src/table/table.js)
 

src/table/column-table.js

@@ -120,11 +120,13 @@ export default class ColumnTable extends Table {
    * Get an array of values contained in a column. The resulting array
    * respects any table filter or orderby criteria.
    * @param {string} name The column name.
-   * @return {import('./table').DataValue[]} The array of column values.
+   * @param {ArrayConstructor|import('./table').TypedArrayConstructor} [arrayConstructor=Array]
+   *  The array constructor for instantiating the output array.
+   * @return {import('./table').DataValue[]|import('./table).TypedArray} The array of column values.
    */
-  columnArray(name) {
+  columnArray(name, arrayConstructor = Array) {
     const column = this.column(name);
-    const array = Array(this.numRows());
+    const array = new arrayConstructor(this.numRows());
     let idx = -1;
     this.scan(row => array[++idx] = column.get(row), true);
     return array;

src/table/table.js

@@ -188,9 +188,11 @@ export default class Table extends Transformable {
    * Get an array of values contained in a column. The resulting array
    * respects any table filter or orderby criteria.
    * @param {string} name The column name.
-   * @return {DataValue[]} The array of column values.
+   * @param {ArrayConstructor|TypedArrayConstructor} [arrayConstructor=Array]
+   *  The array constructor for instantiating the output array.
+   * @return {DataValue[]|TypedArray} The array of column values.
    */
-  columnArray(name) { // eslint-disable-line no-unused-vars
+  columnArray(name, arrayConstructor) { // eslint-disable-line no-unused-vars
     error('Not implemented');
   }
 
@@ -450,6 +452,16 @@ export default class Table extends Transformable {
   }
 }
 
+/**
+ * A typed array constructor.
+ * @typedef {Uint8ArrayConstructor|Uint16ArrayConstructor|Uint32ArrayConstructor|BigUint64ArrayConstructor|Int8ArrayConstructor|Int16ArrayConstructor|Int32ArrayConstructor|BigInt64ArrayConstructor|Float32ArrayConstructor|Float64ArrayConstructor} TypedArrayConstructor
+ */
+
+/**
+ * A typed array instance.
+ * @typedef {Uint8Array|Uint16Array|Uint32Array|BigUint64Array|Int8Array|Int16Array|Int32Array|BigInt64Array|Float32Array|Float64Array} TypedArray
+ */
+
 /**
  * Backing table data.
  * @typedef {object|Array} TableData

test/arrow/profiler-test.js

@@ -2,8 +2,7 @@ import tape from 'tape';
 import { profiler } from '../../src/arrow/encode/profiler';
 import {
   Float64, Int16, Int32, Int64, Int8,
-  Uint16, Uint32, Uint64, Uint8,
-  util
+  Uint16, Uint32, Uint64, Uint8, util
 } from 'apache-arrow';
 
 const { compareTypes } = util;

test/table/column-table-test.js

@@ -156,6 +156,35 @@ tape('ColumnTable supports object output', t => {
   t.end();
 });
 
+tape('ColumnTable supports column array output', t => {
+  const dt = new ColumnTable({
+      u: ['a', 'a', 'a', 'b', 'b'],
+      v: [2, 1, 4, 5, 3]
+    })
+    .filter(d => d.v > 1)
+    .orderby('v');
+
+  t.deepEqual(
+    dt.columnArray('u'),
+    ['a', 'b', 'a', 'b'],
+    'column array, strings'
+  );
+
+  t.deepEqual(
+    dt.columnArray('v'),
+    [2, 3, 4, 5],
+    'column array, numbers'
+  );
+
+  t.deepEqual(
+    dt.columnArray('v', Int32Array),
+    Int32Array.of(2, 3, 4, 5),
+    'column array, typed array'
+  );
+
+  t.end();
+});
+
 tape('ColumnTable supports grouped object output', t => {
   const dt = new ColumnTable({
       u: ['a', 'a', 'a', 'b', 'b'],