Hi,

I need to plot data in log scale (y-axis, lineseries). My data often contains zeros. I've noticed that when this is the case, the y-axis behaves badly. When there is a zero, the minimum value is set to 1.

When all values are smaller than 1 this fails badly (see example)


var rand = new Random();
var rand_seq = Enumerable.Repeat(0, 100).Select(i => rand.NextDouble()).ToArray();
rand_seq[20] = 0;
var chart = new NCartesianChart();
nChartControl1.Charts.Add(chart);
var line = new NLineSeries();
line.DataLabelStyle.Visible = false;
chart.Axis(StandardAxis.PrimaryY).ScaleConfigurator = new NLogarithmicScaleConfigurator();

chart.Series.Add(line);
line.Values.FillFromEnumerable(rand_seq);
nChartControl1.Refresh();


Also, when using larger values than 1, it seems that the value of log(0) is simply set to 1. This tricks the user into believeing that the data point is 1 instead of zero. What I would like, is a solution where points neighboring log(0) simply are plot with a vertical line (i.e. simulating minus infinity).

Is there any way to achieve this?

best regards

Fredrik Östlund

Hi Fredrik,

The behavior of zero values in log axes primarily targets charts with zero scale origin (like bar), which look "good" when zeros are present next to valid values. Sure we can add a mapping function that observes a region of say [0, 0+alpha] and maps it to something that will not generate floating point errors (very large or double.Infinity will cause numeric instability in tick, inflate and other calculations). We'll investigate this further and keep you posted... 

Best Regards,
Nevron Support Team