Javascript 中的元素操作 [英] Element-wise Operations In Javascript

问题描述

我正在做一些物理模拟，其中当然涉及向量.这对我来说变得非常困难，因为据我所知，javascript 不支持这样的东西......

#借助numpy>>>a = np.array([1,2,3])>>>b = np.array([9,2,7])>>>a+b数组([10, 4, 10])

我已经能够通过定义实现相同目的的函数来解决这个限制，但我的公式最终看起来像这样:

add(x, add( mult(v,dt), mult(mult( a(x), .5), Math.pow(dt,2))))

所以我的问题是是否有更好的方法来实现这个功能，它们是我不知道的语言的特性，解决这个问题的库，或者更有效的方法来处理它.

感谢大家的帮助.

解决方案

查看 Sylvester.我想这可能就是你要找的.

但是如果您想自己实现对象，那么最好采用更多的 OOP 方法.JavaScript 是一种基于原型的语言，因此它与其他 OOP 语言略有不同，但它仍然很容易实现您自己的原型.

类似于:

Vector = function(items) {this.items = 物品}Vector.prototype.add = 函数(其他){变量结果 = []for(var i = 0; i < this.items; i++) {result.push( this.items[i] + other.items[i])}返回新向量(结果)；}Vector.prototype.subtract = function(other) {/* 减法代码 */}Vector.prototype.multiply = function(other) {/* 乘法代码 */}

然后像这样使用它们:

var a = new Vector([1,2,3]);var b = new Vector([5,0,1]);var 结果 = a.add(b)result.items//[6,2,4]

或者，如果你愿意，你也可以使用一些函数扩展 Array 类

Array.prototype.vectorAdd = function(other) {/* 添加另一个数组作为向量的代码 */};

并调用它使用

[1,2,3].vectorAdd([5,0,1])

希望这可以为您提供一个起点，让您的代码更具可读性.

另外一个注意事项:不幸的是，在这种情况下，JavaScript 不支持操作重载，因此您不能做像 a+b 这样的整洁的东西.您必须执行类似 a.add(b) 的操作.但是只要你返回一个合适的对象，你就可以将方法链接在一起.喜欢:

a.add(b).multiply(c).subtract(d);

ps.所呈现的代码可能有点偏离"，我只是从头顶上输入它，所以更像对待伪代码 :)

I'm doing some physics simulations which of course involve vectors. This has become very difficult for me because to the best of my knowledge javascript doesn't support anything like this...

#with the aid of numpy
>>> a = np.array([1,2,3])
>>> b = np.array([9,2,7])
>>> a+b
array([10,  4, 10])

I've been able to work around this limitation by defining functions that will achieve the same thing, but my formulas end up looking like this:

add(x, add( mult(v,dt), mult(mult( a(x), .5), Math.pow(dt,2))))

So my question is whether there are better ways to achieve this functionality, whether they be features of the language I am unaware of, libraries that address this issue, or more effective ways to deal with it.

Thanks for the help all.

解决方案

Check out Sylvester. I think it might be what you are looking for.

But if you wanted to implement the objects yourself, then it might be better to do a more OOP approach. JavaScript is a prototype-based language, so it different a little bit from other OOP languages, but its still pretty easy to implement your own prototypes.

Something like:

Vector = function(items) {
    this.items = items
}

Vector.prototype.add = function(other) {
    var result = []
    for(var i = 0; i < this.items; i++) {
        result.push( this.items[i] + other.items[i])
    }

    return new Vector(result);
}

Vector.prototype.subtract = function(other) { /* code to subtract */ }
Vector.prototype.multiply = function(other) { /* code to multiply */ }

And then use them like this:

var a = new Vector([1,2,3]);
var b = new Vector([5,0,1]);

var result = a.add(b)
result.items // [6,2,4]

Or if you wanted to, you could also extend the Array class with some functions with

Array.prototype.vectorAdd = function(other) { /* code to add another array as a vector */ };

And call that using

[1,2,3].vectorAdd([5,0,1])

Hopefully, that might give you a starting point to make your code a little more readable.

Just another note: Unfortunately in this case, JavaScript doesn't support operation overloading so you can't do neat stuff like a+b. You'll have to do something like a.add(b). but as long you return an appropriate object you can chain methods together. Like:

a.add(b).multiply(c).subtract(d);

ps. the presented code might be a little "off", I just typed it up off the top of my head, so treat it more like pseduocode :)

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