Breaking logarithmic yAxis for negative values

[ayanghatak]

Hello,

I am using a licensed CanvasJS version in our enterprise product. And, faced a bug with broken axis. Have tried to narrow down the use-case to the following:

I am trying to create a canvasJS line chart along with a logarithmic yAxis. The data has two timeseries and one of a dataPoint has a slight negative number.
Please refer to the fiddle here – https://jsfiddle.net/AyanGhatak/Lst8ek6c/

Toggle any of these values to understand the issue better.

“logarithmic”: true / false

“y”: -0.000007314814396825603, / 0.000007314814396825603

Lemme know in case you need anything more. Thank you, your help is really appreciated.

[Vishwas R]

@ayanghatak,

A logarithmic axis can only plot positive values. There simply is no way to put negative values or zero on a logarithmic axis.

Fundamental: If 10^L = Z, then L is the logarithm (base 10) of Z. If L is a negative value, then Z is a positive fraction less than 1.0. If L is zero, then Z equals 1.0. If L is greater than 0, then Z is greater than 1.0. Note that there no value of L will result in a value of Z that is zero or negative. Logarithms are simply not defined for zero or negative numbers.

—
Vishwas R
Team CanvasJS

[ayanghatak]

Hi @vishwas,

Thank you, for looking to it. But currently if there are data, that has a negative dataPoint and the axis is in logarithmic, then it should ideally skip that point or at-least not break that along with other series.

e.g. This is a comparison view of same data plotted against Highcharts and CanvasJS under similar conditions.
https://jsfiddle.net/AyanGhatak/Lst8ek6c/9/embedded/result,js

And as this is a generic error handling specific to every log axis implementation, would you consider putting this check on the library end ?

Thanks,
Ayan

[Vishwas R]

@ayanghatak,

Thanks for your comparison and suggestion. We will reconsider this behavior in future releases.

—
Vishwas R
Team CanvasJS