Sort line items on X axis

core/src/index.ts

@@ -8,8 +8,15 @@ import AdjustHeight from './transformer/AdjustHeight';
 import CalculateCoordinates from './transformer/CalculateCoordinates';
 import CalculateStatistics from './transformer/CacluclateStatistics';
 import CompactLines from './transformer/CompactLines';
+import SortXWithinLines from './transformer/SortXWithinLines';
 
-const transformers = [new AdjustHeight(), new CalculateCoordinates(), new CalculateStatistics(), new CompactLines()];
+const transformers = [
+  new AdjustHeight(),
+  new CalculateCoordinates(),
+  new CalculateStatistics(),
+  new CompactLines(),
+  new SortXWithinLines(),
+];
 
 const defaultConfig: Config = {
   pdfjsParams: {

core/src/support/itemUtils.ts

@@ -3,12 +3,14 @@ import Item from '../Item';
 import ItemGroup from './ItemGroup';
 import Page from './Page';
 
+type KeyExtractor = (item: Item) => any;
 type PageItemTransformer = (page: number, items: Item[]) => Item[];
+type LineItemTransformer = (page: number, line: number, items: Item[]) => Item[];
 
-export function groupByPage(items: Item[]): Item[][] {
+function groupBy(items: Item[], extractKey: KeyExtractor): Item[][] {
   return items.reduce((pageItems: Item[][], item: Item) => {
     const lastPageItems = pageItems[pageItems.length - 1];
-    if (!lastPageItems || item.page > lastPageItems[0]?.page) {
+    if (!lastPageItems || extractKey(item) !== extractKey(lastPageItems[0])) {
       pageItems.push([item]);
     } else {
       lastPageItems.push(item);
@@ -17,16 +19,12 @@ export function groupByPage(items: Item[]): Item[][] {
   }, []);
 }
 
+export function groupByPage(items: Item[]): Item[][] {
+  return groupBy(items, (item) => item.page);
+}
+
 export function groupByElement(items: Item[], elementName: string): Item[][] {
-  return items.reduce((groupedItems: Item[][], item: Item) => {
+  return groupBy(items, (item) => item.data[elementName]);
-    const lastGroupItems = groupedItems[groupedItems.length - 1];
-    if (!lastGroupItems || item.data[elementName] !== lastGroupItems[0]?.data[elementName]) {
-      groupedItems.push([item]);
-    } else {
-      lastGroupItems.push(item);
-    }
-    return groupedItems;
-  }, []);
 }
 
 export function transformGroupedByPage(items: Item[], groupedTransformer: PageItemTransformer): Item[] {
@@ -35,6 +33,16 @@ export function transformGroupedByPage(items: Item[], groupedTransformer: PageIt
   );
 }
 
+export function transformGroupedByPageAndLine(items: Item[], groupedTransformer: LineItemTransformer): Item[] {
+  let transformedItems: Item[] = [];
+  groupByPage(items).forEach((pageItems) => {
+    groupByElement(pageItems, 'line').forEach((lineItems) => {
+      transformedItems.push(...groupedTransformer(pageItems[0].page, lineItems[0].data['line'], lineItems));
+    });
+  });
+  return transformedItems;
+}
+
 export function asPages(items: Item[], itemMerger?: ItemMerger): Page[] {
   return groupByPage(items).map((pageItems: Item[]) => {
     let itemGroups: ItemGroup[];

core/src/transformer/SortXWithinLines.ts

@@ -0,0 +1,26 @@
+import Item from '../Item';
+import ItemResult from '../ItemResult';
+import ItemTransformer from './ItemTransformer';
+import TransformContext from './TransformContext';
+import { transformGroupedByPageAndLine } from '../support/itemUtils';
+
+export default class SortXWithinLines extends ItemTransformer {
+  constructor() {
+    super('Sort by X', 'Sorts the items of a line by the x coordinate', {
+      requireColumns: ['line', 'x'],
+      // itemMerger: {
+      //   groupKey: 'line',
+      //   merge: mergeLineItems,
+      // },
+    });
+  }
+
+  transform(_: TransformContext, inputItems: Item[]): ItemResult {
+    return {
+      items: transformGroupedByPageAndLine(inputItems, (_, __, items) => {
+        return items.sort((a, b) => a.data['x'] - b.data['x']);
+      }),
+      messages: [],
+    };
+  }
+}

core/test/support/itemUtils.test.ts

@@ -1,9 +1,16 @@
 import Item from 'src/Item';
 import Page from 'src/support/Page';
-import { groupByPage, groupByElement, transformGroupedByPage, asPages } from 'src/support/itemUtils';
+import {
+  groupByPage,
+  groupByElement,
+  transformGroupedByPage,
+  transformGroupedByPageAndLine,
+  asPages,
+} from 'src/support/itemUtils';
 import ItemGroup from 'src/support/ItemGroup';
 import ItemMerger from 'src/ItemMerger';
 import ItemTransformer from 'src/transformer/ItemTransformer';
+import { items } from 'test/transformer/testItems';
 
 describe('groupByPage', () => {
   test('empty', async () => {
@@ -68,6 +75,30 @@ describe('transformGroupedByPage', () => {
   });
 });
 
+describe('transformGroupedByPageAndLine', () => {
+  test('empty', async () => {
+    const transformedItems = transformGroupedByPageAndLine([], () => fail("shoudln't be called"));
+    expect(transformedItems).toEqual([]);
+  });
+
+  test('transform', async () => {
+    const pageItems = [
+      items(0, [{ line: 1, id: 1 }]),
+      items(1, [
+        { line: 1, id: 2 },
+        { line: 1, id: 3 },
+        { line: 2, id: 4 },
+      ]),
+      items(2, [{ line: 1, id: 5 }]),
+    ];
+    const flattenedItems = new Array<Item>().concat(...pageItems);
+    const transformedItems = transformGroupedByPageAndLine(flattenedItems, (page, line, items) => {
+      return [new Item(0, { group: `${page}/${line}:${items.length}` })];
+    });
+    expect(transformedItems.map((item) => item.data['group'])).toEqual(['0/1:1', '1/1:2', '1/2:1', '2/1:1']);
+  });
+});
+
 describe('asPages', () => {
   test('empty', async () => {
     expect(groupByPage([])).toEqual([]);