Error when normalizing a BigInt variable

[juba]

When data contains a BigInt variable, trying to apply normalize on this variable throws an error: TypeError: Cannot convert a BigInt value to a number.

I've created a small notebook to reproduce the issue:

https://observablehq.com/@juba/plot-normalize-bigint-error

It seems that the error may come from this line, but I'm far from an expert on this domain so I may be mistaken:

https://github.com/observablehq/plot/blob/0032c11160e6340ce44307675d93bed382d10446/src/transforms/normalize.js#L46C1-L47C1

[Fil]

Yes you can fix this example by doing

 function normalizeBasis(basis) {
   return {
     mapIndex(I, S, T) {
-      const b = +basis(I, S);
+      const b = Number(basis(I, S));
       for (const i of I) {
-        T[i] = S[i] === null ? NaN : S[i] / b;
+        T[i] = S[i] === null ? NaN : Number(S[i]) / b;
       }
     }
   };

to try, just run yarn prepublishOnly in your repo, then upload the file to your notebook and add a cell that says:

Plot = require(await FileAttachment("plot.umd.min.js").url())

However I don't think this is enough, because we need to fix all the different bases.

In that case the patch is simpler:

 function normalizeBasis(basis) {
   return {
     mapIndex(I, S, T) {
+      S = S.map(Number);
       const b = +basis(I, S);
       for (const i of I) {
         T[i] = S[i] === null ? NaN : S[i] / b;

but we should avoid doing this if the values are already numbers (not big).

So maybe instead we do:

--- a/src/options.js
+++ b/src/options.js
@@ -54,7 +54,7 @@ function maybeTypedMap(data, f, type) {
   return map(data, isNumberType(type) ? (d, i) => coerceNumber(f(d, i)) : f, type); // allow conversion from BigInt
 }

-function maybeTypedArrayify(data, type) {
+export function maybeTypedArrayify(data, type) {
   return type === undefined
     ? arrayify(data) // preserve undefined type
     : isArrowVector(data)
diff --git a/src/transforms/normalize.js b/src/transforms/normalize.js
index f4d225cd..2f426020 100644
--- a/src/transforms/normalize.js
+++ b/src/transforms/normalize.js
@@ -1,6 +1,6 @@
 import {extent, deviation, max, mean, median, min, sum} from "d3";
 import {defined} from "../defined.js";
-import {percentile, taker} from "../options.js";
+import {maybeTypedArrayify, percentile, taker} from "../options.js";
 import {mapX, mapY} from "./map.js";

 export function normalizeX(basis, options) {
@@ -43,6 +43,7 @@ export function normalize(basis) {
 function normalizeBasis(basis) {
   return {
     mapIndex(I, S, T) {
+      S = maybeTypedArrayify(S, Float64Array);
       const b = +basis(I, S);
       for (const i of I) {
         T[i] = S[i] === null ? NaN : S[i] / b;

[Fil]

Also let's create a more meaningful example / test plot. We often get BigInt as the result of a sql count, so maybe simulate this like so:

classes = d3
  .bin()(olympians.map((d) => d.height))
  .map((bin) => ({ weightclass: bin.x0, count: BigInt(bin.length) }))

// default basis
Plot.barY(
  classes,
  Plot.normalizeY({ x: "weightclass", y: "count" })
).plot({ x: { interval: 0.05 } })

// test a different basis
Plot.barY(
  classes,
  Plot.normalizeY("median", { x: "weightclass", y: "count" })
).plot({ x: { interval: 0.05 } })

[juba]

I can confirm that the issue seems fixed with your PR at https://github.com/observablehq/plot/pull/2155.

Just as a side note, I get these BigInt values because I'm passing arrow data coming from pandas and polars, which themselves seem to now import CSV files with 64 bits integers by default...

Thanks!

[Fil]

thanks. I think I made a mistake in my patch, though. The coercion should happen earlier. Will fix.