javascript - 比较 D3.js 中的两个时间对象

Question

在 D3.js 中，我目前正在尝试根据数据数组是否包含该时间来填充一个空数组(数组仅包含每 5 分钟后的时间戳)。如果数据数组包含时间，则应复制该值，否则为 null。但是当我尝试比较两个时间对象时，它无法正常工作。

以下是代码(当前代码不是复制值而是打印以便于调试):

var data = [{"mytime": "2015-12-01T23:10:00.000Z", "value": 64},
{"mytime": "2015-12-01T23:15:00.000Z", "value": 67},
{"mytime": "2015-12-01T23:20:00.000Z", "value": 70},
{"mytime": "2015-12-01T23:25:00.000Z", "value": 64},
{"mytime": "2015-12-01T23:30:00.000Z", "value": 72},
{"mytime": "2015-12-01T23:35:00.000Z", "value": 75},
{"mytime": "2015-12-01T23:40:00.000Z", "value": 71},
{"mytime": "2015-12-01T23:45:00.000Z", "value": 80},
{"mytime": "2015-12-02T00:00:00.000Z", "value": 80},
{"mytime": "2015-12-02T00:05:00.000Z", "value": 85}
];

var parseDate = d3.time.format("%Y-%m-%dT%H:%M:%S.%LZ").parse;

data.forEach(function(d) {
          d.mytime = parseDate(d.mytime);
 });

var act_data = [];

  var x_extent = d3.extent(data, function(d){
      return d['mytime']});

  time_arr = d3.time.minute.range(x_extent[0],x_extent[1],5);
  for(var key in time_arr){
  var temp;
  temp = contains(data,time_arr[key],'mytime');
}


function contains(data,value,variable)
{
  var i =data.length;
  while(i--){

   if (data[i][variable] === value)
   {
    console.log('found');
    return i;
   } 
  }
  return false;
}

输出应该是这样的:

data = [{"mytime": "2015-12-01T23:10:00.000Z", "value": 64},
{"mytime": "2015-12-01T23:15:00.000Z", "value": 67},
{"mytime": "2015-12-01T23:20:00.000Z", "value": 70},
{"mytime": "2015-12-01T23:25:00.000Z", "value": 64},
{"mytime": "2015-12-01T23:30:00.000Z", "value": 72},
{"mytime": "2015-12-01T23:35:00.000Z", "value": 75},
{"mytime": "2015-12-01T23:40:00.000Z", "value": 71},
{"mytime": "2015-12-01T23:45:00.000Z", "value": 80},
{"mytime": "2015-12-01T23:50:00.000Z", "value": null},
{"mytime": "2015-12-01T23:55:00.000Z", "value": null},
{"mytime": "2015-12-02T00:00:00.000Z", "value": 80},
{"mytime": "2015-12-02T00:05:00.000Z", "value": 85}
];

Answer 1

您可以使用(D3 3.x API)

• d3.time.format解析和格式化您的日期
• d3.extent确定时间戳的边界
• d3.time.scale生成您想要输出的报价
• 和d3.map对您的输入进行哈希处理并确定值是否存在

这给了我们

var data = [...];

// for parsing and formatting
var timeformat = d3.time.format("%Y-%m-%dT%H:%M:%S.%LZ");

// range to operate on
var extent = d3.extent(data, function(d){ 
    return timeformat.parse(d.mytime); 
});

// scale representing the time stamps
var scale = d3.time.scale()
    .domain(extent) // the boundaries
    .ticks(d3.time.minute, 5); // 5 minutes intervals

// easier to determine if a value exists
var hashed = d3.map(data, function(d) { return d.mytime; });

// or if your version < 3.5
/*
var hashed = d3.map();
data.forEach(function(d) { 
    hashed.set(d.mytime, d);
});
*/


// transforms the scale into the desired output
var res = scale.map(function(t) {
    var ft = timeformat(t);
    return {
        mytime: ft,
        value: (hashed.has(ft)) ? hashed.get(ft).value : null
    };
});

还有一个演示 http://jsfiddle.net/nikoshr/qxcLry8z/

var data = [
{"mytime": "2015-12-01T23:10:00.000Z", "value": 64},
{"mytime": "2015-12-01T23:15:00.000Z", "value": 67},
{"mytime": "2015-12-01T23:20:00.000Z", "value": 70},
{"mytime": "2015-12-01T23:25:00.000Z", "value": 64},
{"mytime": "2015-12-01T23:30:00.000Z", "value": 72},
{"mytime": "2015-12-01T23:35:00.000Z", "value": 75},
{"mytime": "2015-12-01T23:40:00.000Z", "value": 71},
{"mytime": "2015-12-01T23:45:00.000Z", "value": 80},
{"mytime": "2015-12-02T00:00:00.000Z", "value": 80},
{"mytime": "2015-12-02T00:05:00.000Z", "value": 85}
];


var timeformat = d3.time.format("%Y-%m-%dT%H:%M:%S.%LZ");

var extent = d3.extent(data, function(d){ 
    return timeformat.parse(d.mytime); 
});

var scale = d3.time.scale()
    .domain(extent)
    .ticks(d3.time.minute, 5);
  
var hashed = d3.map();
data.forEach(function(d) { 
    hashed.set(d.mytime, d);
});
  
var res = scale.map(function(t) {
    var ft = timeformat(t);
    return {
        mytime: ft,
        value: (hashed.has(ft)) ? hashed.get(ft).value : null
    };
});

var $table = $('<table></table>'); 
res.forEach(function(d) {
    $table.append('<tr><td>'+d.mytime+'</td><td>'+d.value+'</td></tr>')
});
$('body').append($table);
  

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>