76 lines
3.0 KiB
JavaScript
76 lines
3.0 KiB
JavaScript
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/** PURE_IMPORTS_START .._operators_groupBy PURE_IMPORTS_END */
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import { groupBy as higherOrder, GroupedObservable } from '../operators/groupBy';
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export { GroupedObservable };
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/* tslint:enable:max-line-length */
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/**
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* Groups the items emitted by an Observable according to a specified criterion,
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* and emits these grouped items as `GroupedObservables`, one
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* {@link GroupedObservable} per group.
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*
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* <img src="./img/groupBy.png" width="100%">
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*
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* @example <caption>Group objects by id and return as array</caption>
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* Observable.of<Obj>({id: 1, name: 'aze1'},
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* {id: 2, name: 'sf2'},
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* {id: 2, name: 'dg2'},
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* {id: 1, name: 'erg1'},
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* {id: 1, name: 'df1'},
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* {id: 2, name: 'sfqfb2'},
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* {id: 3, name: 'qfs3'},
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* {id: 2, name: 'qsgqsfg2'}
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* )
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* .groupBy(p => p.id)
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* .flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], []))
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* .subscribe(p => console.log(p));
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*
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* // displays:
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* // [ { id: 1, name: 'aze1' },
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* // { id: 1, name: 'erg1' },
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* // { id: 1, name: 'df1' } ]
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* //
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* // [ { id: 2, name: 'sf2' },
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* // { id: 2, name: 'dg2' },
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* // { id: 2, name: 'sfqfb2' },
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* // { id: 2, name: 'qsgqsfg2' } ]
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* //
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* // [ { id: 3, name: 'qfs3' } ]
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*
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* @example <caption>Pivot data on the id field</caption>
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* Observable.of<Obj>({id: 1, name: 'aze1'},
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* {id: 2, name: 'sf2'},
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* {id: 2, name: 'dg2'},
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* {id: 1, name: 'erg1'},
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* {id: 1, name: 'df1'},
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* {id: 2, name: 'sfqfb2'},
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* {id: 3, name: 'qfs1'},
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* {id: 2, name: 'qsgqsfg2'}
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* )
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* .groupBy(p => p.id, p => p.name)
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* .flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], ["" + group$.key]))
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* .map(arr => ({'id': parseInt(arr[0]), 'values': arr.slice(1)}))
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* .subscribe(p => console.log(p));
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*
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* // displays:
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* // { id: 1, values: [ 'aze1', 'erg1', 'df1' ] }
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* // { id: 2, values: [ 'sf2', 'dg2', 'sfqfb2', 'qsgqsfg2' ] }
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* // { id: 3, values: [ 'qfs1' ] }
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*
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* @param {function(value: T): K} keySelector A function that extracts the key
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* for each item.
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* @param {function(value: T): R} [elementSelector] A function that extracts the
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* return element for each item.
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* @param {function(grouped: GroupedObservable<K,R>): Observable<any>} [durationSelector]
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* A function that returns an Observable to determine how long each group should
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* exist.
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* @return {Observable<GroupedObservable<K,R>>} An Observable that emits
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* GroupedObservables, each of which corresponds to a unique key value and each
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* of which emits those items from the source Observable that share that key
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* value.
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* @method groupBy
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* @owner Observable
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*/
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export function groupBy(keySelector, elementSelector, durationSelector, subjectSelector) {
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return higherOrder(keySelector, elementSelector, durationSelector, subjectSelector)(this);
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}
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//# sourceMappingURL=groupBy.js.map
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