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Re: how to handle negative data and position values for log scales
From: |
Ben Abbott |
Subject: |
Re: how to handle negative data and position values for log scales |
Date: |
Tue, 09 Nov 2010 08:31:26 +0800 |
On Nov 9, 2010, at 4:17 AM, Rik wrote:
>> Should the change I just pushed be left in place, or shall negative values
>> for different objects be handled differently for each object type for log
>> scale plots?
>>
>> For example, what if text objects for a semilogy plot have a negative
>> y-positions? Perhaps my change should remain and something special be done
>> for text objects?
>>
>> Ben
>>
> Ben,
>
> I think your patch is fine. Although it might be clearer to move the code
> into each of the sub-objects which is affected, it would also create a lot
> of redundancy. When we next need to tweak this issue we'd find ourselves
> hunting through the code to find all the occurrences to update. Your
> current code is concise and represents just one instance to update.
>
> As for negative y-positions, there is currently no support for it at the
> axis level. That would need to be addressed before considering whether
> objects can be placed at negative locations. In my opinion this is too
> small a corner case to worry about. If you're interested though, try
> running a semilog plot on Matlab and forcing the y-axis to display negative
> values. What do they do?
>
> Note that confining placement to the visible axis isn't really much of a
> restriction. For example, the left-axis on the plotyy demo goes to -1, but
> the right-axis is log scale and starts at 10^-1. One can still place
> objects that seem to occur at negative positions relative to the left-axis
> by using the second axis and y-positions that are positive and above 10^-1.
>
> Cheers,
> Rik
I'll favor avoiding redundancy, and leave the patch as it is.
I'll also place the text problem on my list of things to look at.
Ben