mirror of https://gitee.com/bigwinds/arangodb
51 lines
1.7 KiB
JavaScript
51 lines
1.7 KiB
JavaScript
var _append = require('./internal/_append');
|
|
var _curry2 = require('./internal/_curry2');
|
|
var _dispatchable = require('./internal/_dispatchable');
|
|
var _reduce = require('./internal/_reduce');
|
|
var _xgroupBy = require('./internal/_xgroupBy');
|
|
|
|
|
|
/**
|
|
* Splits a list into sub-lists stored in an object, based on the result of calling a String-returning function
|
|
* on each element, and grouping the results according to values returned.
|
|
*
|
|
* Acts as a transducer if a transformer is given in list position.
|
|
* @see R.transduce
|
|
*
|
|
* @func
|
|
* @memberOf R
|
|
* @category List
|
|
* @sig (a -> String) -> [a] -> {String: [a]}
|
|
* @param {Function} fn Function :: a -> String
|
|
* @param {Array} list The array to group
|
|
* @return {Object} An object with the output of `fn` for keys, mapped to arrays of elements
|
|
* that produced that key when passed to `fn`.
|
|
* @example
|
|
*
|
|
* var byGrade = R.groupBy(function(student) {
|
|
* var score = student.score;
|
|
* return score < 65 ? 'F' :
|
|
* score < 70 ? 'D' :
|
|
* score < 80 ? 'C' :
|
|
* score < 90 ? 'B' : 'A';
|
|
* });
|
|
* var students = [{name: 'Abby', score: 84},
|
|
* {name: 'Eddy', score: 58},
|
|
* // ...
|
|
* {name: 'Jack', score: 69}];
|
|
* byGrade(students);
|
|
* // {
|
|
* // 'A': [{name: 'Dianne', score: 99}],
|
|
* // 'B': [{name: 'Abby', score: 84}]
|
|
* // // ...,
|
|
* // 'F': [{name: 'Eddy', score: 58}]
|
|
* // }
|
|
*/
|
|
module.exports = _curry2(_dispatchable('groupBy', _xgroupBy, function groupBy(fn, list) {
|
|
return _reduce(function(acc, elt) {
|
|
var key = fn(elt);
|
|
acc[key] = _append(elt, acc[key] || (acc[key] = []));
|
|
return acc;
|
|
}, {}, list);
|
|
}));
|