有人可以给我提示吗？我想按列表的长度对地图的值进行排序。
var chordtypes = {
"maj": [0, 4, 7],
"M7": [0, 4, 7, 11],
"m7": [0, 3, 7, 10],
"6": [0, 4, 7, 9],
"9": [0, 4, 7, 10, 14],
"sus2": [0, 2, 7],
"sus4": [0, 5, 7],
"omit3": [0, 7],
"#5": [0, 4, 8],
"+7b9#11": [0, 4, 8, 10, 13, 18],
"+9": [0, 4, 8, 10, 14]
};
该函数确实按其长度对列表列表进行排序。
import 'dart:collection';
/// sorts the ListMap (== A Map of List<V>) on the length
/// of the List values.
LinkedHashMap sortListMap(LinkedHashMap map) {
List mapKeys = map.keys.toList(growable : false);
mapKeys.sort((k1, k2) => map[k1].length - map[k2].length);
LinkedHashMap resMap = new LinkedHashMap();
mapKeys.forEach((k1) { resMap[k1] = map[k1] ; }) ;
return resMap;
}
结果：
var res = sortListMap(chordtypes);
print(res);
==>
{ omit3: [0, 7],
maj: [0, 4, 7],
sus2: [0, 2, 7],
sus4: [0, 5, 7],
#5: [0, 4, 8],
M7: [0, 4, 7, 11],
m7: [0, 3, 7, 10],
6: [0, 4, 7, 9],
9: [0, 4, 7, 10, 14],
+9: [0, 4, 8, 10, 14],
+7b9#11: [0, 4, 8, 10, 13, 18] }
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我来说两句