如何从数组中选择某个属性最小的对象？

Question

我刚刚开始了解 Coffescript，并遇到了从数组中选择一个对象的要求，其中特定属性是最小的。我在下面列出了我的基本代码：

class Point
    constructor: (@x, @y, @z) ->

    addedTogether: ->
        @x+@y+@z

class PointCollection
    constructor: ->
        @points = []

    add: (point) ->
        @points.push(point)

    minimalPoint: ->
        // need to return point with lowest addedTogether value

samplePoints = new PointCollection()
samplePoints.add(new Point(1,2,3))
samplePoints.add(new Point(2,3,4))
samplePoints.add(new Point(3,4,5))
samplePoints.add(new Point(4,5,6))
samplePoints.add(new Point(5,6,7))
samplePoints.add(new Point(1,1,1))

lowestValuePoint = samplePoints.minimalPoint()

我显然可以用普通的旧 JavaScript 来实现这一点，其函数如下：

function findPointWithLowestScore(points) {
    var lowestScoringPoint = points[0];

    for (var i = 0; i < points.length; i++) {

    lowestScoringPoint = (points[i].addedTogether() < lowestScoringPoint.addedTogether()) ? points[i] :    lowestScoringPoint;
    }
    return lowestScoringPoint;
}

但是有没有更好、更干净、CoffeeScript-y 的方法来做到这一点？

Answer 1

尝试这样的事情：

class Point
    constructor: (@x, @y, @z) ->

    addedTogether: ->
        @x+@y+@z

class PointCollection
    constructor: ->
        @points = []

    add: (point) ->
        @points.push(point)

    minimalPoint: ->
        tmp = @points.slice 0 # duplicate array
        tmp.sort (a, b) -> a.addedTogether() - b.addedTogether() # Sort from lowest to highest
        tmp[0] # Return the first element

samplePoints = new PointCollection()
samplePoints.add(new Point(1,2,3))
samplePoints.add(new Point(2,3,4))
samplePoints.add(new Point(3,4,5))
samplePoints.add(new Point(4,5,6))
samplePoints.add(new Point(5,6,7))
samplePoints.add(new Point(1,1,1))

lowestValuePoint = samplePoints.minimalPoint()

Answer 2

你可以试试这个：

class PointCollection
    # ...
    compare: (p1, p2) -> p1.addedTogether() - p2.addedTogether()

    minimalPoint: ->
        minPoint = points[0]
        minVal = if compare(minPoint, point) > 0 then point else minPoint for point in points