Breaking logarithmic yAxis for negative values

• March 29, 2019 at 11:22 am #24766
  
  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.

  March 29, 2019 at 4:45 pm #24770
  
  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

  March 29, 2019 at 6:47 pm #24773
  
  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

  April 1, 2019 at 6:45 pm #24790
  
  Vishwas R

  @ayanghatak,

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

  —
  Vishwas R
  Team CanvasJS