d3.js：5942错误：的值无效 <g> 属性transform =“ translate（NaN，0）”

Question

Using d3.js v3.55, crossfilter.js v1.311 and dc.js v1.73 and trying to build an reduce function that returns an average as opposed to a sum or count. The reduceSum which is builtin working fine, but when I try to add my own reduce function, based on many examples on the internet. I receive the messages: d3.js:5942 Error: Invalid value for attribute transform="translate(NaN,0)" d3.js:8718 Error: Invalid value for attribute width="NaN"

Here is the code reduced as much as I can without eliminating any important information:

<script type="text/javascript">
//
// Create the Chart Objects
//
var GeoZoneChart               = dc.rowChart("#chart-geo-zone");
var pdcData = [
{GeoZone: 'New York Metro', PDCLast365: 0.43}, 
{GeoZone: 'New York Metro', PDCLast365: 0.427}, 
{GeoZone: 'New York Metro', PDCLast365: 0.418}, 
{GeoZone: 'Los Angeles Metro', PDCLast365: 0.4085}, 
{GeoZone: 'Los Angeles Metro', PDCLast365: 0.40565}, 
{GeoZone: 'Chicago Metro', PDCLast365: 0.46789457}, 
{GeoZone: 'Chicago Metro', PDCLast365: 0.46366023}, 
{GeoZone: 'Chicago Metro', PDCLast365: 0.447781455}
];
//
// normalize/parse data
//   in this case, turn the decimel into a percentage
pdcData.forEach(function(d) {
    d.PDCLast365 = d.PDCLast365 * 100;
    d.PDCLast365 = d.PDCLast365.toFixed(2);
});

function isNumeric(n) {
  return !isNaN(parseFloat(n)) && isFinite(n);
}

function reduceAddAvg(attr) {
  return function(p,v) {
    if (isNumeric(v[attr]) ){
        ++p.count;
        p.sum += v[attr];
        p.avg = p.sum/p.count;
    }
    return p;
  };
}
function reduceRemoveAvg(attr) {
  return function(p,v) {
    if (isNumeric(v[attr]) ){
        --p.count;
        p.sum -= v[attr];
        p.avg = p.sum/p.count;
    }
    return p;
  };
}
function reduceInitAvg() {
  return {count:0, sum:0, avg:0};
}

//
// set crossfilter
//
var ndx = crossfilter(pdcData),
    GeoZoneDim           = ndx.dimension(function(d) {return d.GeoZone;}),
    PDCLast365PerGeoZone = 
          GeoZoneDim.group().reduce(
            reduceAddAvg('PDCLast365'), 
            reduceRemoveAvg('PDCLast365'), 
            reduceInitAvg);


GeoZoneChart
    .width(400).height(200)
    .dimension(GeoZoneDim)
    .group(PDCLast365PerGeoZone)
    .elasticX(true);

dc.renderAll();
</script>

Answer 1

You need a guard for when p.count falls to zero. So:

function reduceRemoveAvg(attr) {
  return function(p,v) {
    if (isNumeric(v[attr]) ){
        --p.count;
        p.sum -= v[attr];
        p.avg = p.count ? p.sum/p.count : 0;
    }
    return p;
  };
}

Obliged if you can point to any such bad examples here on SO or on the dc.js site or user group.

EDIT: I'm not sure what effect it will have here, but toFixed() actually returns a string, not a number. And your isNumeric tests whether the value can be converted to a number, not whether it is a number. So you might end up with string concatenation not addition.

Like I say below, the right way to figure this or is by putting breakpoints in the reduce functions and seeing what's actually being calculated.

Answer 2

I usually get that Error when the range is not an Array.

Check if the variable that .range receives is an actual Array