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Posted to commits@echarts.apache.org by GitBox <gi...@apache.org> on 2022/02/19 15:13:28 UTC

[GitHub] [echarts] andreasgerstmayr opened a new pull request #16547: feat(chart): support negative values in logarithmic axes

andreasgerstmayr opened a new pull request #16547:
URL: https://github.com/apache/echarts/pull/16547


   The logarithm of negative values is not defined.
   However, in the case of a logarithmic chart axis, it makes sense to
   define log(-x) as -log(x), to support logarithmic axes with negative
   values.
   
   Cf. 'symlog' in matplotlib
   
   Resolves: #15558
   
   <!-- Please fill in the following information to help us review your PR more efficiently. -->
   
   ## Brief Information
   
   This pull request is in the type of:
   
   - [ ] bug fixing
   - [X] new feature
   - [ ] others
   
   
   
   ### What does this PR do?
   
   Supports negative values in logarithmic axes.
   
   
   
   ### Fixed issues
   
   - #15558
   
   
   ## Details
   
   ### Before: What was the problem?
   
   Axes with logarithmic scales didn't support negative values, because `Math.log()` of a negative number is undefined (`NaN`). Therefore the ticks on the yAxis disappeared entirely.
   
   
   
   ### After: How is it fixed in this PR?
   
   Negative values for logarithmic scales work by defining `log(-x) = -log(x)` and negative values are shown on logarithmic axes.
   
   
   
   ## Misc
   
   ### Related test cases or examples to use the new APIs
   
   `test/bar-log-negative.html`
   
   
   
   ## Others
   
   ### Merging options
   
   - [ ] Please squash the commits into a single one when merging.
   
   ### Other information
   


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[GitHub] [echarts] echarts-bot[bot] commented on pull request #16547: feat(chart): support negative values in logarithmic axes

Posted by GitBox <gi...@apache.org>.
echarts-bot[bot] commented on pull request #16547:
URL: https://github.com/apache/echarts/pull/16547#issuecomment-1046040296


   Thanks for your contribution!
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