Question

您好我在从我的数据文件中过滤掉最新数据时遇到了问题。我有以下数据

var data=
[
{"id":1,"speed":50,time:10:51.30},
{"id":1,"speed":40,time:10:51.40},
{"id":1,"speed":60,time:10:51.50},
{"id":1,"speed":55,time:10:51.55},
{"id":2,"speed":55,time:10:51.50},
{"id":2,"speed":65,time:10:51.58}
]

我想过滤掉数据，以便在最近的时间内显示或显示数据。所以我的过滤数据应包含以下内容

var filtereddata=
[
{"id":1,"speed":55,time:10:51.55},
{"id":2,"speed":65,time:10:51.58}
]

如何使用crossfilter从数据中获取过滤后的数据？我正在尝试

var ndx=crossfilter(data);
var dim=ndx.dimension(function(d){return d.time;});
var filter=dim.filter(function(d){d3.max(data,function(d){return d.time;})});

但它不起作用？我该怎么办？

Answer 1

问题是您正在查看过滤器对象。您需要使用顶部或底部将过滤的dim转换为数组。

请参阅下面的代码或更好地查看Here的工作版本。

var data=[
{id:1,speed:50, time: new Date('2011-04-11T11:51:00')},
{id:2,speed:40, time: new Date('2011-04-11T11:51:10')},
{id:3,speed:60, time: new Date('2011-04-11T11:51:20')},
{id:4,speed:51, time: new Date('2011-04-11T11:51:30')},
{id:5,speed:55, time: new Date('2011-04-11T11:51:40')},
{id:6,speed:65, time: new Date('2011-04-11T11:51:50')}];




var ndx = crossfilter(data);
var dataByTime = ndx.dimension(function (d) {
    return d.time;
});

var dataBySpeed = ndx.dimension(function (d) {
    return d.speed;
});

//var speedFilter = dataBySpeed.filter(function (d) {});

var timeFilter = dataByTime.filter(function(d){});

//console.log(speedFilter.filterRange([40, 55]).top(3));
console.log(timeFilter.filterRange([new Date('2011-04-11T11:51:00'), new Date('2011-04-11T11:51:40')]).top(3));

<强> ______ UPDATE _____

好的，我明白你的意思了。请参阅下面的更新代码段。我还更新了solution at jsfiddle

var data=[
{id:1,speed:50, time: new Date('2011-04-11T11:51:00')},
{id:2,speed:40, time: new Date('2011-04-11T11:51:10')},
{id:2,speed:60, time: new Date('2011-04-11T11:51:20')},
{id:3,speed:51, time: new Date('2011-04-11T11:51:30')},
{id:3,speed:55, time: new Date('2011-04-11T11:51:40')},
{id:3,speed:65, time: new Date('2011-04-11T11:51:50')}];

var uniqueVals = new Map();
data.forEach(function(d){ 
    var existingVal = uniqueVals.get(d.id);
    if (existingVal){
        if (existingVal.time < d.time){
            uniqueVals.set(d.id, d);
        }
    } else {
        uniqueVals.set(d.id, d);
    }
    });

var finalData = [];
uniqueVals.forEach(function(d){ finalData.push(d); });
console.log(uniqueVals);

最近一次JSON数据的交叉过滤

1 个答案: