如何从某个属性最小的数组中选择一个对象？答案

【问题标题】：How to select an object from an array where a certain property is minimal?如何从某个属性最小的数组中选择一个对象？
【发布时间】：2012-02-24 01:45:24
【问题描述】：

我刚刚开始了解 Coffescript，并且遇到了从特定属性最少的数组中选择对象的要求。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()

我显然可以在普通的旧 javascript 中使用如下函数来做到这一点：

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 的方式来做到这一点？

【问题讨论】：

标签： javascript arrays coffeescript

【解决方案1】：

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

【讨论】：

【解决方案2】：

试试这样的：

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()

【讨论】：

这很好，谢谢，tmp= @points.slice 0 行可以替换为 tmp = @points[..] ，这是同一件事的简写，但我认为读起来更好。