elasticY does not work if all values are negative (ordinal x axis)

[jtsherba]

I believe I have found a little bug.

For an ordinal bar chart with only negative values, the bar for the highest value does not draw correctly.

The issue is not present when there are one or more positive values included.

See example here: https://jsfiddle.net/tjsd4yqs/6/

[jtsherba]

Never mind, just needed to set the y axis domain to start from 0.

[gordonwoodhull]

Thanks @jtsherba. I think there is a bug here, because .elasticY(true) does not work if all values are negative.

https://jsfiddle.net/tjsd4yqs/12/

Retitling.

[arjain]

Are your aware of any workarounds to make elasticY work with negative values?

[sebgrohn]

We recently ran into this issue in our product as well, both with bar charts and row charts. After some investigation, we think that the following changes would fix the issue:

• For bar charts and others using Stack mixin, change dc.stackMixin.yAxisMax to behave like yAxisMin, capping each stack's value to at least y0 / 0:

  _chart.yAxisMax = function () {
      var max = d3.max(flattenStack(), function (p) {
          return (p.y + p.y0 > p.y0) ? (p.y + p.y0) : p.y0;
      });
  
      return dc.utils.add(max, _chart.yAxisPadding());
  };

• For row chart, add a condition in calculateAxisScale in dc.rowChart for the domain max, like the one for the minimum:

  function calculateAxisScale () {
      if (!_x || _elasticX) {
          var extent = d3.extent(_rowData, _chart.cappedValueAccessor);
          if (extent[0] > 0) {
              extent[0] = 0;
          }
          if (extent[1] < 0) {
              extent[1] = 0;
          }
          _x = d3.scale.linear().domain(extent)
              .range([0, _chart.effectiveWidth()]);
      }
      _xAxis.scale(_x);
  }

• Other chart types that don't use Stack mixin and should have a corresponding fix?

I would be happy to prepare a proper PR in the beginning of next week, if you think this is the way to go. :)

Ping @stillesjo

[sebgrohn]

I have opened a PR (#1156) with the proposed solution above, but there are some issues that need to be discussed. All input is welcome!

[sebgrohn]

@gordonwoodhull: what do you think about this solution?

[gordonwoodhull]

Fixed by #1156 in 2.0 beta 32.