60 lines
1.7 KiB
JavaScript
60 lines
1.7 KiB
JavaScript
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import _checkForMethod from "./internal/_checkForMethod.js";
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import _curry2 from "./internal/_curry2.js";
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import reduceBy from "./reduceBy.js";
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/**
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* Splits a list into sub-lists stored in an object, based on the result of
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* calling a String-returning function on each element, and grouping the
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* results according to values returned.
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*
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* Dispatches to the `groupBy` method of the second argument, if present.
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*
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* Acts as a transducer if a transformer is given in list position.
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*
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* @func
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* @memberOf R
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* @since v0.1.0
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* @category List
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* @sig (a -> String) -> [a] -> {String: [a]}
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* @param {Function} fn Function :: a -> String
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* @param {Array} list The array to group
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* @return {Object} An object with the output of `fn` for keys, mapped to arrays of elements
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* that produced that key when passed to `fn`.
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* @see R.reduceBy, R.transduce
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* @example
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*
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* const byGrade = R.groupBy(function(student) {
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* const score = student.score;
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* return score < 65 ? 'F' :
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* score < 70 ? 'D' :
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* score < 80 ? 'C' :
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* score < 90 ? 'B' : 'A';
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* });
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* const students = [{name: 'Abby', score: 84},
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* {name: 'Eddy', score: 58},
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* // ...
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* {name: 'Jack', score: 69}];
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* byGrade(students);
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* // {
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* // 'A': [{name: 'Dianne', score: 99}],
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* // 'B': [{name: 'Abby', score: 84}]
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* // // ...,
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* // 'F': [{name: 'Eddy', score: 58}]
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* // }
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*/
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var groupBy =
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/*#__PURE__*/
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_curry2(
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/*#__PURE__*/
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_checkForMethod('groupBy',
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/*#__PURE__*/
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reduceBy(function (acc, item) {
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if (acc == null) {
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acc = [];
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}
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acc.push(item);
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return acc;
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}, null)));
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export default groupBy;
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