support Apache Arrow as a normalized data representation (#2115)

* columnar support for arrow tables

* defer reading the values until they're actually requested (which is often not the case)

* tests

* comment

* fix apache arrow dates (alternative to #2096)

* add test snapshot

* fix test wrt apache/arrow#40718

* arrow table data; fix BigInt coercion

* more arrow support

* arrow date hint; fix BigInt coercion

* inline floater

* shorten slightly

* valueof tests; better arrow coercion

* Arrow-aware stack transform

* a few more dataify

* fix merge conflict

* fix Plot.find and stack customOrder

* handle Arrow in a few more places

---------

Co-authored-by: Philippe Rivière <fil@rezo.net>

Author: mbostock

package.json

@@ -56,6 +56,7 @@
     "@types/node": "^20.5.0",
     "@typescript-eslint/eslint-plugin": "^7.2.0",
     "@typescript-eslint/parser": "^7.2.0",
+    "apache-arrow": "^16.0.2",
     "c8": "^9.1.0",
     "canvas": "^2.0.0",
     "d3-geo-projection": "^4.0.0",

src/interactions/pointer.js

@@ -1,5 +1,6 @@
 import {pointer as pointof} from "d3";
 import {composeRender} from "../mark.js";
+import {isArray} from "../options.js";
 import {applyFrameAnchor} from "../style.js";
 
 const states = new WeakMap();
@@ -126,7 +127,11 @@ function pointerK(kx, ky, {x, y, px, py, maxRadius = 40, channels, render, ...op
 
         // Dispatch the value. When simultaneously exiting this facet and
         // entering a new one, prioritize the entering facet.
-        if (!(i == null && facetState?.size > 1)) context.dispatchValue(i == null ? null : data[i]);
+        if (!(i == null && facetState?.size > 1)) {
+          const value = i == null ? null : isArray(data) ? data[i] : data.get(i);
+          context.dispatchValue(value);
+        }
+
         return r;
       }
 

src/mark.d.ts

@@ -32,6 +32,7 @@ export type TipPointer = "x" | "y" | "xy";
  *
  * - an array, typed array, or other iterable
  * - an object with a length property and indexed values
+ * - an Apache Arrow Table
  */
 export type Data = Iterable<any> | ArrayLike<any>;
 

src/mark.js

@@ -2,7 +2,7 @@ import {channelDomain, createChannels, valueObject} from "./channel.js";
 import {defined} from "./defined.js";
 import {maybeFacetAnchor} from "./facet.js";
 import {maybeClip, maybeNamed, maybeValue} from "./options.js";
-import {arrayify, isDomainSort, isObject, isOptions, keyword, range, singleton} from "./options.js";
+import {dataify, isDomainSort, isObject, isOptions, keyword, range, singleton} from "./options.js";
 import {project} from "./projection.js";
 import {maybeClassName, styles} from "./style.js";
 import {basic, initializer} from "./transforms/basic.js";
@@ -89,10 +89,10 @@ export class Mark {
     }
   }
   initialize(facets, facetChannels, plotOptions) {
-    let data = arrayify(this.data);
+    let data = dataify(this.data);
     if (facets === undefined && data != null) facets = [range(data)];
     const originalFacets = facets;
-    if (this.transform != null) ({facets, data} = this.transform(data, facets, plotOptions)), (data = arrayify(data));
+    if (this.transform != null) ({facets, data} = this.transform(data, facets, plotOptions)), (data = dataify(data));
     if (facets !== undefined) facets.original = originalFacets; // needed to read facetChannels
     const channels = createChannels(this.channels, data);
     if (this.sort != null) channelDomain(data, facets, channels, facetChannels, this.sort); // mutates facetChannels!

src/options.js

@@ -7,14 +7,36 @@ import {timeInterval, utcInterval} from "./time.js";
 export const TypedArray = Object.getPrototypeOf(Uint8Array);
 const objectToString = Object.prototype.toString;
 
+export function isArray(value) {
+  return value instanceof Array || value instanceof TypedArray;
+}
+
+function isNumberArray(value) {
+  return value instanceof TypedArray && !isBigIntArray(value);
+}
+
+function isNumberType(type) {
+  return type?.prototype instanceof TypedArray && !isBigIntType(type);
+}
+
+function isBigIntArray(value) {
+  return value instanceof BigInt64Array || value instanceof BigUint64Array;
+}
+
+function isBigIntType(type) {
+  return type === BigInt64Array || type === BigUint64Array;
+}
+
 // If a reindex is attached to the data, channel values expressed as arrays will
 // be reindexed when the channels are instantiated. See exclusiveFacets.
 export const reindex = Symbol("reindex");
 
 export function valueof(data, value, type) {
   const valueType = typeof value;
   return valueType === "string"
-    ? maybeTypedMap(data, field(value), type)
+    ? isArrowTable(data)
+      ? maybeTypedArrowify(data.getChild(value), type)
+      : maybeTypedMap(data, field(value), type)
     : valueType === "function"
     ? maybeTypedMap(data, value, type)
     : valueType === "number" || value instanceof Date || valueType === "boolean"
@@ -29,21 +51,25 @@ function maybeTake(values, index) {
 }
 
 function maybeTypedMap(data, f, type) {
-  return map(data, type?.prototype instanceof TypedArray ? floater(f) : f, type);
+  return map(data, isNumberType(type) ? (d, i) => coerceNumber(f(d, i)) : f, type); // allow conversion from BigInt
 }
 
 function maybeTypedArrayify(data, type) {
   return type === undefined
     ? arrayify(data) // preserve undefined type
+    : isArrowVector(data)
+    ? maybeTypedArrowify(data, type)
     : data instanceof type
     ? data
-    : type.prototype instanceof TypedArray && !(data instanceof TypedArray)
-    ? type.from(data, coerceNumber)
-    : type.from(data);
+    : type.from(data, isNumberType(type) && !isNumberArray(data) ? coerceNumber : undefined);
 }
 
-function floater(f) {
-  return (d, i) => coerceNumber(f(d, i));
+function maybeTypedArrowify(vector, type) {
+  return vector == null
+    ? vector
+    : (type === undefined || type === Array) && isArrowDateType(vector.type)
+    ? coerceDates(vector.toArray())
+    : maybeTypedArrayify(vector.toArray(), type);
 }
 
 export const singleton = [null]; // for data-less decoration marks, e.g. frame
@@ -70,7 +96,7 @@ export function percentile(reduce) {
 
 // If the values are specified as a typed array, no coercion is required.
 export function coerceNumbers(values) {
-  return values instanceof TypedArray ? values : map(values, coerceNumber, Float64Array);
+  return isNumberArray(values) ? values : map(values, coerceNumber, Float64Array);
 }
 
 // Unlike Mark’s number, here we want to convert null and undefined to NaN since
@@ -95,7 +121,7 @@ export function coerceDate(x) {
     ? x
     : typeof x === "string"
     ? isoParse(x)
-    : x == null || isNaN((x = +x))
+    : x == null || isNaN((x = Number(x))) // allow conversion from BigInt
     ? undefined
     : new Date(x);
 }
@@ -130,9 +156,15 @@ export function keyword(input, name, allowed) {
   return i;
 }
 
+// Like arrayify, but also allows data to be an Apache Arrow Table.
+export function dataify(data) {
+  return isArrowTable(data) ? data : arrayify(data);
+}
+
 // Promotes the specified data to an array as needed.
 export function arrayify(values) {
-  if (values == null || values instanceof Array || values instanceof TypedArray) return values;
+  if (values == null || isArray(values)) return values;
+  if (isArrowVector(values)) return maybeTypedArrowify(values);
   switch (values.type) {
     case "FeatureCollection":
       return values.features;
@@ -233,22 +265,21 @@ export function maybeZ({z, fill, stroke} = {}) {
   return z;
 }
 
+export function lengthof(data) {
+  return isArray(data) ? data.length : data?.numRows;
+}
+
 // Returns a Uint32Array with elements [0, 1, 2, … data.length - 1].
 export function range(data) {
-  const n = data.length;
+  const n = lengthof(data);
   const r = new Uint32Array(n);
   for (let i = 0; i < n; ++i) r[i] = i;
   return r;
 }
 
-// Returns a filtered range of data given the test function.
-export function where(data, test) {
-  return range(data).filter((i) => test(data[i], i, data));
-}
-
 // Returns an array [values[index[0]], values[index[1]], …].
 export function take(values, index) {
-  return map(index, (i) => values[i], values.constructor);
+  return isArray(values) ? map(index, (i) => values[i], values.constructor) : map(index, (i) => values.at(i));
 }
 
 // If f does not take exactly one argument, wraps it in a function that uses take.
@@ -575,3 +606,30 @@ export function maybeClip(clip) {
   else if (clip != null) clip = keyword(clip, "clip", ["frame", "sphere"]);
   return clip;
 }
+
+// https://github.com/observablehq/stdlib/blob/746ca2e69135df6178e4f3a17244def35d8d6b20/src/arrow.js#L4C1-L17C1
+function isArrowTable(value) {
+  return (
+    value &&
+    typeof value.getChild === "function" &&
+    typeof value.toArray === "function" &&
+    value.schema &&
+    Array.isArray(value.schema.fields)
+  );
+}
+
+function isArrowVector(value) {
+  return value && typeof value.toArray === "function" && value.type;
+}
+
+// Apache Arrow now represents dates as numbers. We currently only support
+// implicit coercion to JavaScript Date objects when the numbers represent
+// milliseconds since Unix epoch.
+function isArrowDateType(type) {
+  return (
+    type &&
+    (type.typeId === 8 || // date
+      type.typeId === 10) && // timestamp
+    type.unit === 1 // millisecond
+  );
+}

src/plot.js

@@ -10,7 +10,7 @@ import {axisFx, axisFy, axisX, axisY, gridFx, gridFy, gridX, gridY} from "./mark
 import {frame} from "./marks/frame.js";
 import {tip} from "./marks/tip.js";
 import {isColor, isIterable, isNone, isScaleOptions} from "./options.js";
-import {arrayify, map, yes, maybeIntervalTransform, subarray} from "./options.js";
+import {dataify, lengthof, map, yes, maybeIntervalTransform, subarray} from "./options.js";
 import {createProjection, getGeometryChannels, hasProjection} from "./projection.js";
 import {createScales, createScaleFunctions, autoScaleRange, exposeScales} from "./scales.js";
 import {innerDimensions, outerDimensions} from "./scales.js";
@@ -459,7 +459,7 @@ function maybeTopFacet(facet, options) {
   if (facet == null) return;
   const {x, y} = facet;
   if (x == null && y == null) return;
-  const data = arrayify(facet.data);
+  const data = dataify(facet.data);
   if (data == null) throw new Error("missing facet data");
   const channels = {};
   if (x != null) channels.fx = createChannel(data, {value: x, scale: "fx"});
@@ -478,7 +478,7 @@ function maybeMarkFacet(mark, topFacetState, options) {
   // here with maybeTopFacet that we could reduce.
   const {fx, fy} = mark;
   if (fx != null || fy != null) {
-    const data = arrayify(mark.data ?? fx ?? fy);
+    const data = dataify(mark.data ?? fx ?? fy);
     if (data === undefined) throw new Error(`missing facet data in ${mark.ariaLabel}`);
     if (data === null) return; // ignore channel definitions if no data is provided TODO this right?
     const channels = {};
@@ -500,7 +500,7 @@ function maybeMarkFacet(mark, topFacetState, options) {
   if (
     data.length > 0 &&
     (groups.size > 1 || (groups.size === 1 && channels.fx && channels.fy && [...groups][0][1].size > 1)) &&
-    arrayify(mark.data)?.length === data.length
+    lengthof(dataify(mark.data)) === lengthof(data)
   ) {
     warn(
       `Warning: the ${mark.ariaLabel} mark appears to use faceted data, but isn’t faceted. The mark data has the same length as the facet data and the mark facet option is "auto", but the mark data and facet data are distinct. If this mark should be faceted, set the mark facet option to true; otherwise, suppress this warning by setting the mark facet option to false.`

src/transforms/basic.js

@@ -1,6 +1,7 @@
 import {randomLcg} from "d3";
 import {ascendingDefined, descendingDefined} from "../defined.js";
-import {arrayify, isDomainSort, isOptions, maybeValue, valueof} from "../options.js";
+import {isArray, isDomainSort, isOptions} from "../options.js";
+import {dataify, maybeValue, valueof} from "../options.js";
 
 export function basic({filter: f1, sort: s1, reverse: r1, transform: t1, initializer: i1, ...options} = {}, transform) {
   // If both t1 and t2 are defined, returns a composite transform that first
@@ -40,7 +41,7 @@ function composeTransform(t1, t2) {
   if (t2 == null) return t1 === null ? undefined : t1;
   return function (data, facets, plotOptions) {
     ({data, facets} = t1.call(this, data, facets, plotOptions));
-    return t2.call(this, arrayify(data), facets, plotOptions);
+    return t2.call(this, dataify(data), facets, plotOptions);
   };
 }
 
@@ -101,7 +102,9 @@ function sortTransform(value) {
 
 function sortData(compare) {
   return (data, facets) => {
-    const compareData = (i, j) => compare(data[i], data[j]);
+    const compareData = isArray(data)
+      ? (i, j) => compare(data[i], data[j])
+      : (i, j) => compare(data.get(i), data.get(j));
     return {data, facets: facets.map((I) => I.slice().sort(compareData))};
   };
 }

src/transforms/exclusiveFacets.js

@@ -1,9 +1,9 @@
-import {reindex, slice} from "../options.js";
+import {lengthof, reindex, slice} from "../options.js";
 
 export function exclusiveFacets(data, facets) {
   if (facets.length === 1) return {data, facets}; // only one facet; trivially exclusive
 
-  const n = data.length;
+  const n = lengthof(data);
   const O = new Uint8Array(n);
   let overlaps = 0;
 

src/transforms/group.js

@@ -1,37 +1,9 @@
-import {
-  InternSet,
-  deviation,
-  group as grouper,
-  max,
-  maxIndex,
-  mean,
-  median,
-  min,
-  minIndex,
-  mode,
-  rollup,
-  sort,
-  sum,
-  variance
-} from "d3";
+import {InternSet, group as grouper, rollup, sort} from "d3";
+import {deviation, max, maxIndex, mean, median, min, minIndex, mode, sum, variance} from "d3";
 import {ascendingDefined} from "../defined.js";
-import {
-  column,
-  identity,
-  isObject,
-  isTemporal,
-  labelof,
-  maybeApplyInterval,
-  maybeColorChannel,
-  maybeColumn,
-  maybeInput,
-  maybeTuple,
-  percentile,
-  range,
-  second,
-  take,
-  valueof
-} from "../options.js";
+import {maybeApplyInterval, maybeColorChannel, maybeColumn, maybeInput, maybeTuple} from "../options.js";
+import {isArray, isObject, isTemporal} from "../options.js";
+import {column, identity, labelof, percentile, range, second, take, valueof} from "../options.js";
 import {basic} from "./basic.js";
 
 // Group on {z, fill, stroke}.
@@ -444,7 +416,7 @@ export function find(test) {
   if (typeof test !== "function") throw new Error(`invalid test function: ${test}`);
   return {
     reduceIndex(I, V, {data}) {
-      return V[I.find((i) => test(data[i], i, data))];
+      return V[I.find(isArray(data) ? (i) => test(data[i], i, data) : (i) => test(data.get(i), i, data))];
     }
   };
 }

src/transforms/stack.js

@@ -2,7 +2,7 @@ import {InternMap, cumsum, greatest, group, groupSort, max, min, rollup, sum} fr
 import {ascendingDefined, descendingDefined} from "../defined.js";
 import {withTip} from "../mark.js";
 import {maybeApplyInterval, maybeColumn, maybeZ, maybeZero} from "../options.js";
-import {column, field, mid, one, range, valueof} from "../options.js";
+import {column, field, isArray, lengthof, mid, one, range, valueof} from "../options.js";
 import {basic} from "./basic.js";
 import {exclusiveFacets} from "./exclusiveFacets.js";
 
@@ -91,7 +91,7 @@ function stack(x, y = one, kx, ky, {offset, order, reverse}, options) {
       const Y = valueof(data, y, Float64Array);
       const Z = valueof(data, z);
       const compare = order && order(data, X, Y, Z);
-      const n = data.length;
+      const n = lengthof(data);
       const Y1 = setY1(new Float64Array(n));
       const Y2 = setY2(new Float64Array(n));
       const facetstacks = [];
@@ -252,7 +252,7 @@ function maybeOrder(order, offset, ky) {
     return orderAccessor(field(order));
   }
   if (typeof order === "function") return (order.length === 1 ? orderAccessor : orderComparator)(order);
-  if (Array.isArray(order)) return orderGiven(order);
+  if (isArray(order)) return orderGiven(order);
   throw new Error(`invalid order: ${order}`);
 }
 
@@ -327,7 +327,9 @@ function orderAccessor(f) {
 }
 
 function orderComparator(f) {
-  return (data) => (i, j) => f(data[i], data[j]);
+  return (data) => {
+    return isArray(data) ? (i, j) => f(data[i], data[j]) : (i, j) => f(data.get(i), data.get(j));
+  };
 }
 
 function orderGiven(domain) {