Question

上周我遇到了一些我正在做的简单程序的问题，而且有人帮我了。现在我遇到了另一个问题。我目前有这个代码：

＆＃13;

var findItem = function(desiredItem) {
    var items = [
        { item: "rusty nail", probability: 0.25 },
        { item: "stone", probability: 0.23 },
        { item: "banana", probability: 0.20 },
        { item: "leaf", probability: 0.17 },
        { item: "mushroom", probability: 0.10 },
        { item: "diamond", probability: 0.05 }
    ];
    var possible = items.some( ({item, probability}) => 
          item === desiredItem && probability > 0 );
    if (!possible) {
        console.log('There is no chance you\'ll ever find a ' + desiredItem);
        return;
    }
    var sum = items.reduce( (sum, {item, probability}) => sum+probability, 0 );
    while (true) {
        var value = Math.random() * sum;
        var lootedItem = items.find( 
                ({item, probability}) => (value -= probability) <= 0 ).item;
        if (lootedItem === 'diamond') break;
        console.log("Dang! A " + lootedItem + " was found...");
    }
    console.log("Lucky! A " + desiredItem + " was found!");
}

findItem('diamond');

＆＃13;

现在，我想通过向category数组添加另一个名为items的值来扩展此功能。我希望类别的值为2，5或10。因此，我们假设diamond项属于category: 10，执行findItem时，只能找到属于同一类别的项目。我现在已经尝试了几天，但似乎无法理解它。也许有人可以帮我推动正确的方向？提前致谢

Answer 1

您可以将此更新用于该代码：

example.domain.tld to domain.tld/foo/example-foo.html

变化是：

将更多参数传递给您的函数：项目列表和所需类别
在项目列表中应用过滤器作为函数
修复了有关example.domain.tld/foo/测试的问题 - 它有“钻石”硬编码。
定义函数外部的项列表，并为每个元素添加类别值。
调整函数的调用以传递额外的参数。

Answer 2

你想要这样的东西吗？

＆＃13;

var items = [ { item: "rusty nail", probability: 0.25, category: 10 }
            , { item: "stone",      probability: 0.23, category:  5 }
            , { item: "banana",     probability: 0.20, category:  2 }
            , { item: "leaf",       probability: 0.17, category:  5 }
            , { item: "mushroom",   probability: 0.10, category:  2 }
            , { item: "diamond",    probability: 0.05, category: 10 }
            ];

findItem("diamond", items);

function findItem(needle, haystack) {
    var item = haystack.find(thing => thing.item === needle &&
                                       thing.probability > 0);

    if (item) {
        var category = item.category;
        var items = haystack.filter(thing => thing.category === category);
        var sum = items.reduce((sum, thing) => sum + thing.probability, 0);

        var value = sum * Math.random();
        var loot = items.find(thing => (value -= thing.probability) <= 0).item;

        while (loot !== needle) {
            value = sum * Math.random();
            console.log("Dang! A " + loot + " was found...");
            loot = items.find(thing => (value -= thing.probability) <= 0).item;
        }

        return console.log("Lucky! A " + needle + " was found!");
    }

    console.log("There's no chance that you'll ever find a " + needle);
}

＆＃13;

与您的代码唯一的主要区别是我使用filter来限制搜索。

使用加权概率和值在数组中查找项目

2 个答案: