Address review feedback in CI typecheck fixes

Agent-Logs-Url: https://github.com/githubnext/tsessebe/sessions/2715e479-20de-4885-bb80-bc9bbae1f654

Co-authored-by: mrjf <180956+mrjf@users.noreply.github.com>

Author: Copilot

src/core/align.ts

@@ -125,7 +125,7 @@ export function alignSeries<L extends Scalar, R extends Scalar>(
   left: Series<L>,
   right: Series<R>,
   options: AlignSeriesOptions = {},
-): [Series<Scalar>, Series<Scalar>] {
+): [Series<L>, Series<R>] {
   const { join = "outer", fillValue = null } = options;
   const targetIdx = resolveIndex(left.index, right.index, join);
 

src/core/base-index.ts

@@ -70,8 +70,8 @@ export class Index<T extends Label = Label> {
   }
 
   /** Snapshot of the underlying values as a plain array. */
-  get values(): T[] {
-    return [...this._values];
+  get values(): readonly T[] {
+    return this._values;
   }
 
   /** True when every label appears exactly once. */

src/core/frame.ts

@@ -888,27 +888,15 @@ function reindexColumns(
 ): Map<string, Series<Scalar>> {
   const result = new Map<string, Series<Scalar>>();
   for (const [name, series] of colMap) {
-    if (series.size === newIndex.size) {
-      result.set(
-        name,
-        new Series({
-          data: series.values,
-          index: newIndex,
-          dtype: series.dtype,
-          ...(series.name !== null ? { name: series.name } : {}),
-        }),
+    if (series.size !== newIndex.size) {
+      throw new RangeError(
+        `Index length ${newIndex.size} does not match data length ${series.size} for column "${name}"`,
       );
-      continue;
-    }
-
-    const resized: Scalar[] = new Array<Scalar>(newIndex.size);
-    for (let i = 0; i < newIndex.size; i++) {
-      resized[i] = series.values[i] ?? null;
     }
     result.set(
       name,
       new Series({
-        data: resized,
+        data: series.values,
         index: newIndex,
         dtype: series.dtype,
         ...(series.name !== null ? { name: series.name } : {}),

src/core/reindex.ts

@@ -252,7 +252,7 @@ export function reindexSeries<T extends Scalar>(
   series: Series<T>,
   newIndex: readonly Label[] | Index<Label>,
   options: ReindexSeriesOptions = {},
-): Series<Scalar> {
+): Series<T> {
   const { fillValue = null, method, limit } = options;
 
   const newIdx = toIndex(newIndex);
@@ -279,8 +279,8 @@ export function reindexSeries<T extends Scalar>(
   const finalValues =
     method !== undefined ? applyFillMethod(resultValues, present, method, limit) : resultValues;
 
-  return new Series<Scalar>({
-    data: finalValues,
+  return new Series<T>({
+    data: finalValues as T[],
     index: newIdx,
     name: series.name,
   });

src/groupby/groupby.ts

@@ -340,7 +340,25 @@ export class DataFrameGroupBy {
         throw new TypeError(`aggNamed: "${outCol}" must be a NamedAgg`);
       }
       const src = named.column;
-      const fn = resolveAgg(named.aggfunc as AggName | AggFn);
+      const aggSpec = named.aggfunc;
+      let fn: AggFn;
+      if (typeof aggSpec === "function") {
+        fn = resolveAgg(aggSpec);
+      } else if (
+        aggSpec === "sum" ||
+        aggSpec === "mean" ||
+        aggSpec === "min" ||
+        aggSpec === "max" ||
+        aggSpec === "count" ||
+        aggSpec === "std" ||
+        aggSpec === "first" ||
+        aggSpec === "last" ||
+        aggSpec === "size"
+      ) {
+        fn = resolveAgg(aggSpec);
+      } else {
+        throw new TypeError(`aggNamed: unsupported aggfunc "${aggSpec}" for column "${outCol}"`);
+      }
       const srcSeries = this._df.col(src);
       const srcVals = srcSeries.values as readonly Scalar[];
       resultCols[outCol] = this._groups.map((g) => fn(g.positions.map((p) => srcVals[p] as Scalar)));

src/groupby/named_agg.ts

@@ -40,9 +40,9 @@ export class NamedAgg {
   /** Source column to read from the DataFrame. */
   readonly column: string;
   /** Aggregation to apply — a built-in name or a custom function. */
-  readonly aggfunc: AggName | AggFn | string;
+  readonly aggfunc: AggName | AggFn;
 
-  constructor(column: string, aggfunc: AggName | AggFn | string) {
+  constructor(column: string, aggfunc: AggName | AggFn) {
     this.column = column;
     this.aggfunc = aggfunc;
   }
@@ -59,7 +59,7 @@ export class NamedAgg {
  * });
  * ```
  */
-export function namedAgg(column: string, aggfunc: AggName | AggFn | string): NamedAgg {
+export function namedAgg(column: string, aggfunc: AggName | AggFn): NamedAgg {
   return new NamedAgg(column, aggfunc);
 }
 

src/stats/crosstab.ts

@@ -202,7 +202,7 @@ export function crosstab(
   const buckets: Array<Array<number[] | undefined>> | null =
     values !== undefined
       ? Array.from({ length: nRows }, () =>
-          Array.from({ length: nCols }, () => undefined as number[] | undefined),
+          Array.from<undefined, number[] | undefined>({ length: nCols }, () => undefined),
         )
       : null;
 

tests/core/align.test.ts

@@ -4,11 +4,12 @@ import { DataFrame } from "../../src/core/frame.ts";
 import { Index } from "../../src/core/base-index.ts";
 import { Series } from "../../src/core/series.ts";
 import { alignSeries, alignDataFrame } from "../../src/core/align.ts";
+import type { Scalar } from "../../src/index.ts";
 
 // ─── helpers ──────────────────────────────────────────────────────────────────
 
-function ns(data: number[], labels: string[], name?: string): Series<number> {
-  return new Series<number>({
+function ns(data: number[], labels: string[], name?: string): Series<Scalar> {
+  return new Series<Scalar>({
     data,
     index: new Index<string>(labels),
     name: name ?? null,

tests/core/reindex.test.ts

@@ -4,15 +4,16 @@ import { DataFrame } from "../../src/core/frame.ts";
 import { Index } from "../../src/core/base-index.ts";
 import { Series } from "../../src/core/series.ts";
 import { reindexDataFrame, reindexSeries } from "../../src/core/reindex.ts";
+import type { Scalar } from "../../src/index.ts";
 
 // ─── helpers ──────────────────────────────────────────────────────────────────
 
 function makeNumericSeries(
   data: number[],
   labels: string[],
   name?: string,
-): Series<number> {
-  return new Series<number>({
+): Series<Scalar> {
+  return new Series<Scalar>({
     data,
     index: new Index<string>(labels),
     name: name ?? null,

tests/groupby/named_agg.test.ts

@@ -5,6 +5,7 @@ import { describe, expect, it } from "bun:test";
 import fc from "fast-check";
 import { DataFrame, NamedAgg, isNamedAggSpec, namedAgg } from "../../src/index.ts";
 import type { Scalar } from "../../src/types.ts";
+import type { AggName } from "../../src/groupby/index.ts";
 
 // ─── helpers ──────────────────────────────────────────────────────────────────
 
@@ -270,7 +271,7 @@ describe("NamedAgg property tests", () => {
     fc.assert(
       fc.property(
         fc.string({ minLength: 1 }),
-        fc.constantFrom("sum", "mean", "min", "max", "count" as const),
+        fc.constantFrom<AggName>("sum", "mean", "min", "max", "count"),
         (col, agg) => {
           const spec = new NamedAgg(col, agg);
           expect(spec.column).toBe(col);