arrays - 计算数组中出现的次数

Question

我想计算 ActionScript 3.0 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 etc.

我从另一个类似的问题中得到这段代码:

    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”的计数。您需要为每个项目设置变量 (var appleCount=getCount(fruit, "apples"))。但是，如果您有成百上千个水果名称，不可能为每个水果都写下新变量。

我是 AS3 的新手，所以请原谅我。请在您的代码中包含清晰的注释，因为我想理解代码。

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