define(function (require) {
var zrUtil = require('zrender/core/util');
/**
* nest helper used to group by the array.
* can specified the keys and sort the keys.
*/
function nest() {
var keysFunction = [];
var sortKeysFunction = [];
/**
* map an Array into the mapObject.
* @param {Array} array
* @param {number} depth
*/
function map(array, depth) {
if (depth >= keysFunction.length) {
return array;
}
var i = -1;
var n = array.length;
var keyFunction = keysFunction[depth++];
var mapObject = {};
var valuesByKey = {};
while (++i < n) {
var keyValue = keyFunction(array[i]);
var values = valuesByKey[keyValue];
if (values) {
values.push(array[i]);
}
else {
valuesByKey[keyValue] = [array[i]];
}
}
zrUtil.each(valuesByKey, function (value, key) {
mapObject[key] = map(value, depth);
});
return mapObject;
}
/**
* transform the Map Object to multidimensional Array
* @param {Object} map
* @param {number} depth
*/
function entriesMap(mapObject, depth) {
if (depth >= keysFunction.length) {
return mapObject;
}
var array = [];
var sortKeyFunction = sortKeysFunction[depth++];
zrUtil.each(mapObject, function (value, key) {
array.push({
key: key, values: entriesMap(value, depth)
});
});
if (sortKeyFunction) {
return array.sort(function (a, b) {
return sortKeyFunction(a.key, b.key);
});
}
else {
return array;
}
}
return {
/**
* specified the key to groupby the arrays.
* users can specified one more keys.
* @param {Function} d
*/
key: function (d) {
keysFunction.push(d);
return this;
},
/**
* specified the comparator to sort the keys
* @param {Function} order
*/
sortKeys: function (order) {
sortKeysFunction[keysFunction.length - 1] = order;
return this;
},
/**
* the array to be grouped by.
* @param {Array} array
*/
entries: function (array) {
return entriesMap(map(array, 0), 0);
}
};
}
return nest;
});
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