chore: use builtin flatMap and flat over lodash's flatten

baker/chunk.tsx

@@ -1,4 +1,3 @@
-import { flatten } from "@ourworldindata/utils"
 import chunk from "chunk-text"
 
 export const chunkWords = (text: string, maxChunkLength: number): string[] =>
@@ -11,13 +10,12 @@ export const chunkSentences = (
     // See https://stackoverflow.com/a/25736082/1983739
     // Not perfect, just works in most cases
     const sentenceRegex = /(?<!\w\.\w.)(?<![A-Z][a-z]\.)(?<=\.|\?|\n)\s/g
-    const sentences = flatten(
-        text
-            .split(sentenceRegex)
-            .map((s) =>
-                s.length > maxChunkLength ? chunkWords(s, maxChunkLength) : s
-            )
-    )
+    const sentences = text
+        .split(sentenceRegex)
+        .flatMap((s) =>
+            s.length > maxChunkLength ? chunkWords(s, maxChunkLength) : s
+        )
+
         .map((s) => s.trim())
         .filter((s) => s)
         .reverse() as string[]
@@ -49,15 +47,11 @@ export const chunkParagraphs = (
     text: string,
     maxChunkLength: number
 ): string[] => {
-    const paragraphs = flatten(
-        text
-            .split("\n\n")
-            .map((p) =>
-                p.length > maxChunkLength
-                    ? chunkSentences(p, maxChunkLength)
-                    : p
-            )
-    )
+    const paragraphs = text
+        .split("\n\n")
+        .flatMap((p) =>
+            p.length > maxChunkLength ? chunkSentences(p, maxChunkLength) : p
+        )
         .map((p) => p.trim())
         .filter((p) => p)
         .reverse() as string[]

db/model/Gdoc/htmlToEnriched.ts

@@ -47,14 +47,7 @@ import {
     EnrichedBlockAllCharts,
 } from "@ourworldindata/utils"
 import { match, P } from "ts-pattern"
-import {
-    compact,
-    flatten,
-    get,
-    isArray,
-    isPlainObject,
-    partition,
-} from "lodash"
+import { compact, get, isArray, isPlainObject, partition } from "lodash"
 import cheerio from "cheerio"
 import { spansToSimpleString } from "./gdocUtils.js"
 
@@ -1811,8 +1804,8 @@ export function withoutEmptyOrWhitespaceOnlyTextBlocks(
 export function joinBlockParseResults<T>(
     results: BlockParseResult<T>[]
 ): BlockParseResult<T> {
-    const errors = flatten(results.map((r) => r.errors))
-    const content = flatten(results.map((r) => r.content))
+    const errors = results.flatMap((r) => r.errors)
+    const content = results.flatMap((r) => r.content)
     return { errors, content }
 }
 

explorer/Explorer.tsx

@@ -35,7 +35,6 @@ import {
     DimensionProperty,
     excludeUndefined,
     exposeInstanceOnWindow,
-    flatten,
     identity,
     isInIFrame,
     keyBy,
@@ -1131,9 +1130,9 @@ export class Explorer
 
     @computed get entityPickerColumnDefs(): CoreColumnDef[] {
         const allColumnDefs = uniqBy(
-            flatten(
-                Array.from(this.explorerProgram.columnDefsByTableSlug.values())
-            ),
+            Array.from(
+                this.explorerProgram.columnDefsByTableSlug.values()
+            ).flat(),
             (def) => def.slug
         )
 

packages/@ourworldindata/core-table/src/CoreTable.ts

@@ -5,7 +5,6 @@ import {
     range,
     difference,
     intersection,
-    flatten,
     sum,
     uniqBy,
     intersectionOfSets,
@@ -341,7 +340,7 @@ export class CoreTable<
     }
 
     toOneDimensionalArray(): any {
-        return flatten(this.toTypedMatrix().slice(1))
+        return this.toTypedMatrix().slice(1).flat()
     }
 
     private setColumn(def: COL_DEF_TYPE): void {
@@ -1431,7 +1430,7 @@ export class CoreTable<
 
     concat(tables: CoreTable[], message: string = `Combined tables`): this {
         const all = [this, ...tables] as CoreTable[]
-        const defs = flatten(all.map((table) => table.defs)) as COL_DEF_TYPE[]
+        const defs = all.flatMap((table) => table.defs) as COL_DEF_TYPE[]
         const uniqDefs = uniqBy(defs, (def) => def.slug)
         return this.transform(
             concatColumnStores(

packages/@ourworldindata/core-table/src/OwidTable.ts

@@ -4,7 +4,6 @@ import {
     intersectionOfSets,
     findClosestTimeIndex,
     sumBy,
-    flatten,
     uniq,
     sortNumeric,
     last,
@@ -155,11 +154,9 @@ export class OwidTable extends CoreTable<OwidRow, OwidColumnDef> {
         // todo: should be easy to speed up if necessary.
         return sortNumeric(
             uniq(
-                flatten(
-                    this.getColumns(columnSlugs)
-                        .filter((col) => col)
-                        .map((col) => col.uniqTimesAsc)
-                )
+                this.getColumns(columnSlugs)
+                    .filter((col) => col)
+                    .flatMap((col) => col.uniqTimesAsc)
             )
         )
     }
@@ -441,50 +438,45 @@ export class OwidTable extends CoreTable<OwidRow, OwidColumnDef> {
                 )
             return def
         })
-        const newRows = flatten(
-            Object.values(
-                groupBy(
-                    this.sortedByTime.rows,
-                    (row) => row[this.entityNameSlug]
-                )
-            ).map((rowsForSingleEntity) => {
-                columnSlugs.forEach((valueSlug) => {
-                    let comparisonValue: number
-                    rowsForSingleEntity = rowsForSingleEntity.map(
-                        (row: Readonly<OwidRow>) => {
-                            const newRow = {
-                                ...row,
-                            }
-
-                            const value = row[valueSlug]
-
-                            if (row[timeColumnSlug] < startTimeBound) {
-                                newRow[valueSlug] =
-                                    ErrorValueTypes.MissingValuePlaceholder
-                            } else if (!isNumber(value)) {
-                                newRow[valueSlug] =
-                                    ErrorValueTypes.NaNButShouldBeNumber
-                            } else if (comparisonValue !== undefined) {
-                                // Note: comparisonValue can be negative!
-                                // +value / -comparisonValue = negative growth, which is incorrect.
-                                newRow[valueSlug] =
-                                    (100 * (value - comparisonValue)) /
-                                    Math.abs(comparisonValue)
-                            } else if (value === 0) {
-                                newRow[valueSlug] =
-                                    ErrorValueTypes.MissingValuePlaceholder
-                            } else {
-                                comparisonValue = value
-                                newRow[valueSlug] = 0
-                            }
-
-                            return newRow
+        const newRows = Object.values(
+            groupBy(this.sortedByTime.rows, (row) => row[this.entityNameSlug])
+        ).flatMap((rowsForSingleEntity) => {
+            columnSlugs.forEach((valueSlug) => {
+                let comparisonValue: number
+                rowsForSingleEntity = rowsForSingleEntity.map(
+                    (row: Readonly<OwidRow>) => {
+                        const newRow = {
+                            ...row,
                         }
-                    )
-                })
-                return rowsForSingleEntity
+
+                        const value = row[valueSlug]
+
+                        if (row[timeColumnSlug] < startTimeBound) {
+                            newRow[valueSlug] =
+                                ErrorValueTypes.MissingValuePlaceholder
+                        } else if (!isNumber(value)) {
+                            newRow[valueSlug] =
+                                ErrorValueTypes.NaNButShouldBeNumber
+                        } else if (comparisonValue !== undefined) {
+                            // Note: comparisonValue can be negative!
+                            // +value / -comparisonValue = negative growth, which is incorrect.
+                            newRow[valueSlug] =
+                                (100 * (value - comparisonValue)) /
+                                Math.abs(comparisonValue)
+                        } else if (value === 0) {
+                            newRow[valueSlug] =
+                                ErrorValueTypes.MissingValuePlaceholder
+                        } else {
+                            comparisonValue = value
+                            newRow[valueSlug] = 0
+                        }
+
+                        return newRow
+                    }
+                )
             })
-        )
+            return rowsForSingleEntity
+        })
 
         return this.transform(
             newRows,

packages/@ourworldindata/core-table/src/Transforms.ts

@@ -1,10 +1,4 @@
-import {
-    flatten,
-    ColumnSlug,
-    zip,
-    uniq,
-    cloneDeep,
-} from "@ourworldindata/utils"
+import { ColumnSlug, zip, uniq, cloneDeep } from "@ourworldindata/utils"
 import {
     ErrorValue,
     CoreColumnDef,
@@ -209,7 +203,7 @@ const rollingAverage: Transform = {
             currentValues.push(value)
             currentTimes.push(time)
         }
-        return flatten(groups)
+        return groups.flat()
     },
 }
 

packages/@ourworldindata/grapher/src/barCharts/DiscreteBarChart.tsx

@@ -6,7 +6,6 @@ import {
     sortBy,
     exposeInstanceOnWindow,
     uniq,
-    flatten,
     Bounds,
     DEFAULT_BOUNDS,
     Time,
@@ -683,10 +682,8 @@ export class DiscreteBarChart
     }
 
     @computed private get columnsAsSeries(): DiscreteBarItem[] {
-        return flatten(
-            this.yColumns.map((col) =>
-                this.constructSeries(col, col.validRowIndices.slice(0, 1))
-            )
+        return this.yColumns.flatMap((col) =>
+            this.constructSeries(col, col.validRowIndices.slice(0, 1))
         )
     }
 

packages/@ourworldindata/grapher/src/core/LegacyToOwidTable.ts

@@ -19,7 +19,6 @@ import {
 import {
     diffDateISOStringInDays,
     difference,
-    flatten,
     getYearFromISOStringAndDayOffset,
     intersection,
     isNumber,
@@ -46,10 +45,8 @@ export const legacyToOwidTableAndDimensions = (
 ): { dimensions: OwidChartDimensionInterface[]; table: OwidTable } => {
     // Entity meta map
 
-    const entityMeta = flatten(
-        [...json.values()].map(
-            (value) => value.metadata.dimensions.entities.values
-        )
+    const entityMeta = [...json.values()].flatMap(
+        (value) => value.metadata.dimensions.entities.values
     )
     const entityMetaById: OwidEntityKey = Object.fromEntries(
         entityMeta.map((entity) => [entity.id.toString(), entity])

packages/@ourworldindata/grapher/src/facetChart/FacetChart.tsx

@@ -4,7 +4,6 @@ import {
     Bounds,
     DEFAULT_BOUNDS,
     excludeUndefined,
-    flatten,
     getIdealGridParams,
     max,
     maxBy,
@@ -719,11 +718,11 @@ export class FacetChart
 
     @computed get numericLegendData(): ColorScaleBin[] {
         if (!this.isNumericLegend || !this.hideFacetLegends) return []
-        const allBins: ColorScaleBin[] = flatten(
-            this.externalLegends.map((legend) => [
+        const allBins: ColorScaleBin[] = this.externalLegends.flatMap(
+            (legend) => [
                 ...(legend.numericLegendData ?? []),
                 ...(legend.categoricalLegendData ?? []),
-            ])
+            ]
         )
         const uniqBins = this.getUniqBins(allBins)
         const sortedBins = sortBy(
@@ -735,12 +734,12 @@ export class FacetChart
 
     @computed get categoricalLegendData(): CategoricalBin[] {
         if (this.isNumericLegend || !this.hideFacetLegends) return []
-        const allBins: CategoricalBin[] = flatten(
-            this.externalLegends.map((legend) => [
+        const allBins: CategoricalBin[] = this.externalLegends
+            .flatMap((legend) => [
                 ...(legend.numericLegendData ?? []),
                 ...(legend.categoricalLegendData ?? []),
             ])
-        ).filter((bin) => bin instanceof CategoricalBin) as CategoricalBin[]
+            .filter((bin) => bin instanceof CategoricalBin) as CategoricalBin[]
         const uniqBins = this.getUniqBins(allBins)
         const newBins = uniqBins.map(
             // remap index to ensure it's unique (the above procedure can lead to duplicates)

packages/@ourworldindata/grapher/src/horizontalColorLegend/HorizontalColorLegends.tsx

@@ -7,7 +7,6 @@ import {
     min,
     max,
     last,
-    flatten,
     sum,
     dyFromAlign,
     removeAllWhitespace,
@@ -781,7 +780,7 @@ export class HorizontalCategoricalColorLegend extends HorizontalColorLegend {
             })
         })
 
-        return flatten(lines.map((l) => l.marks))
+        return lines.flatMap((l) => l.marks)
     }
 
     @computed get height(): number {

packages/@ourworldindata/grapher/src/lineCharts/LineChart.tsx

@@ -10,7 +10,6 @@ import {
     getRelativeMouse,
     pointsToPath,
     minBy,
-    flatten,
     last,
     exposeInstanceOnWindow,
     round,
@@ -369,7 +368,7 @@ export class LineChart
     }
 
     @computed private get allValues(): LinePoint[] {
-        return flatten(this.placedSeries.map((series) => series.points))
+        return this.placedSeries.flatMap((series) => series.points)
     }
 
     @observable tooltipState = new TooltipState<{
@@ -1130,19 +1129,17 @@ export class LineChart
     }
 
     @computed get series(): readonly LineChartSeries[] {
-        return flatten(
-            this.yColumns.map((col) =>
-                col.uniqEntityNames.map(
-                    (entityName): LineChartSeries =>
-                        this.constructSingleSeries(entityName, col)
-                )
+        return this.yColumns.flatMap((col) =>
+            col.uniqEntityNames.map(
+                (entityName): LineChartSeries =>
+                    this.constructSingleSeries(entityName, col)
             )
         )
     }
 
     // TODO: remove, seems unused
     @computed get allPoints(): LinePoint[] {
-        return flatten(this.series.map((series) => series.points))
+        return this.series.flatMap((series) => series.points)
     }
 
     @computed get placedSeries(): PlacedLineChartSeries[] {