Question

给出此数据集here

Date    Origin  Destination Delay (mins)
03/01/2001 13:05:00 MCI MDW 8
03/01/2001 13:45:00 LAS PHX 95
03/01/2001 18:30:00 LAX PHX 10
03/01/2001 18:30:00 ONT PHX 0
03/01/2001 18:30:00 LAS LAX -9
03/01/2001 18:30:00 LAX OAK 12
03/01/2001 18:40:00 ONT SMF -8
03/01/2001 19:00:00 MDW BNA -1
03/01/2001 19:00:00 OAK LAX -10
03/01/2001 19:00:00 LAS LAX -11
...

如何汇总Delay字段中的所有值？我知道有负值，我只是以此为例。

我正在考虑使用crossfilter来做这个但不确定是否有一种简单的方法来做这个只是编写一个javascript函数。例如，我可以获得低于2692的总记录/行

cf.size()
//2692

注意
打开控制台模式（Ctrl-shift-I）并键入cf.size()
交叉过滤器已在源代码（Ctrl-U）var cf = crossfilter(data);

中定义

EDIT1

使用d3.sum

d3.sum(data,function(d){return d.delay;})
30632

使用array.reduce - 参见JavaScript Array.prototype.reduce - 什么是0？

data.reduce(function(total,d){ return total+ d.delay }, 0)
30632

使用crossfilter，但这只是在交叉滤波器延迟维var delayDimension = cf.dimension(function(d) {return d.delay;});

上使用上面的减少

delayDimension.top(Infinity).reduce(function(total,d){ return total+ d.delay }, 0)
30632

注意：

这将返回最后一个元素中的延迟值：

data.reduce(function(total,num){ return num.delay })
165

EDIT2

适应这个： Custom calculated aggregated field in Crossfilter

创建维度：

origin=cf.dimension(function(d) { return d.origin; })

创建我的reduceAdd，reduceMove和reduceInitial函数：

var reduceAdd = function(p, v) {
    p.delay += v.delay;
    return p;
}

var reduceRemove = function(p, v) {
    p.delay -= v.delay;
    return p;
}

var reduceInitial = function() {
    return {
        delay : 0
    }
}

来自控制台的示例输出：

var json = origin.group().reduce(reduceAdd,reduceRemove,reduceInitial).orderNatural().top(Infinity);
undefined
json
[Objectkey: "ALB"value: Objectdelay: -1__proto__: Object__proto__: Object, Objectkey: "AMA"value: Objectdelay: 171__proto__: Object__proto__: Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object]
json[0]
Object {key: "ALB", value: Object}
json[0].value
Object {delay: -1}

另一个好人在这里： What are the reduceAdd, reduceSum , reduceRemove functions in crossfilter? How should they be used?但仍然不是我想要的，这是每个类别的总和，我想要总和，例如期望所有延迟值的答案都为30632。

EDIT3

从控制台下面的docs打印输出中获取：

cf.size()
//2692

var reduceAdd = function(p, v) {
    p.delay += v.delay;
    return p;
}

var reduceRemove = function(p, v) {
    p.delay -= v.delay;
    return p;
}

var reduceInitial = function() {
    return {
        delay : 0
    }
}

cf_groupAll=cf.groupAll().reduce(reduceAdd,reduceRemove,reduceInitial)
//Object {}

cf_groupAll.value()
//Object {delay: 30632}

cf_groupAll.value().delay
//30632

Answer 1

您可以使用jQuery Selector获取最后一列的值。然后你可以使用parseInt（STRING，10）来解析Integer值。然后你可以轻松地将它们统计在一起。

var $elements = $('#data tr.item td:last-child')
var sum = 0
$elements.each(function() {
  var currentValue = parseInt($(this).html(), 10)
  sum += currentValue
})

使用crossfilter汇总字段的所有值？

EDIT1

EDIT2

EDIT3

1 个答案: