计算数组中出现的次数

Question

我想计算ActionScript 3.0中数组中出现的次数.说我有

var item:Array = ["apples", "oranges", "grapes", "oranges", "apples", "grapes"];

如何让它显示匹配字符串的数量？例如,结果:apples = 2,oranges = 2等.

我从另一个类似的问题得到了这个代码:

    private function getCount(fruitArray:Array, fruitName:String):int {
    var count:int=0;
    for (var i:int=0; i<fruitArray.length; i++) {
        if(fruitArray[i].toLowerCase()==fruitName.toLowerCase()) {
            count++;
        }
    }
    return count;
}

var fruit:Array = ["apples", "oranges", "grapes", "oranges", "apples", "grapes"];
var appleCount=getCount(fruit, "apples"); //returns 2
var grapeCount=getCount(fruit, "grapes"); //returns 2
var orangeCount=getCount(fruit, "oranges"); //returns 2

在这段代码中,如果你想得到说"苹果"的数量.您需要为每个项目设置变量(var appleCount = getCount(fruit,"apples")).但是,如果你有成百上千的水果名称,就不可能为每一个水果写下新的变量.

我是AS3的新手,请原谅我.请在代码中包含明确的注释,因为我想了解代码.

Answer 1

    var item:Array = ["apples", "oranges", "grapes", "oranges", "apples", "grapes"];

    //write the count number of occurrences of each string into the map {fruitName:count}
    var fruit:String;
    var map:Object = {}; //create the empty object, that will hold the values of counters for each fruit, for example map["apples"] will holds the counter for "apples"

    //iterate for each string in the array, and increase occurrence counter for this string by 1 
    for each(fruit in item)
    {
        //first encounter of fruit name, assign counter to 1
        if(!map[fruit])
            map[fruit] = 1;
        //next encounter of fruit name, just increment the counter by 1
        else
            map[fruit]++;
    }

    //iterate by the map properties to trace the results 
    for(fruit in map)
    {
        trace(fruit, "=", map[fruit]);
    }

输出:

apples = 2
grapes = 2
oranges = 2