[yt-users] question about transfer function colorbar

[Sam Skillman]

Hi Michael,

That looks like a bug to me. I'll take a look at it in more detail
tomorrow.  If you have a fix that works, let us know...

Sam


On Wed, May 21, 2014 at 8:17 AM, Michael Zingale <
michael.zingale at stonybrook.edu> wrote:

> I looked at this some more.  It is this line in vert_cbar that adds the
> odd-valued colorbar label:
>
> xticks = np.append(visible[-1], xticks)
>
> in particular, that adds the "255" value into the xticks array.
>  Interestingly, xticks has a 256 value with the correct x_format() behavior
> (mapping to 1.e7, the upper limit of my transfer function), but that is
> ignored, since it is outside of the bounds of the color bar.
>
> So the question then is why when I setup a transfer function via:
>
>     tf =  yt.visualization.volume_rendering.api.ColorTransferFunction((mi,
> ma))
>
> with mi = -1.e7 and ma = 1.e7, does it map -1.e7 into index 0 in the
> palette and 1.e7 into 256 in the palette, instead of 255?
>
>
> On Sun, May 11, 2014 at 6:03 PM, Michael Zingale <
> michael.zingale at stonybrook.edu> wrote:
>
>> I poked around that code earlier but didn't see anything odd.  I'll look
>> some more at it tomorrow.
>>
>>
>> On Sat, May 10, 2014 at 11:31 AM, Chris Malone <chris.m.malone at gmail.com>wrote:
>>
>>> Hi Mike,
>>>
>>> The number that is getting set (~9.92e6) is just one bin off from the
>>> maximum value (you have a range of 2e7 and the default is 256 bins).  The
>>> code that displays the colorbar, as best I can tell, occurs when you call
>>> save_annotated.  This method eventually calls
>>> ColorTransferFunction.vert_cbar where the ticks and limits are applied to
>>> the colorbar axes object.
>>>
>>> Looking over the logic in that code, it is not immediately obvious to me
>>> why the index is off.  I suspect is has something to do with how the
>>> `visible` variable is defined, but I'd need to play with a dataset and some
>>> print statements...
>>>
>>> Chris
>>>
>>>
>>> On Wed, May 7, 2014 at 8:17 PM, Michael Zingale <
>>> michael.zingale at stonybrook.edu> wrote:
>>>
>>>> I'm trying to show the transfer function on a volume render.  Plotting
>>>> a velocity component, I set the transfer function with 4 Gaussians all with
>>>> the same width.  The range of the transfer function is -1.e7 to 1.e7, but
>>>> for some reason, when output, the upper label in the colorbar is not 1.e7
>>>> but a bit lower (9.92e6).  I am not sure where the code is that draws this,
>>>> and I am confused why it is not setting the tick at 1.e7. It gets the
>>>> bottom tick right.
>>>> Here's an image:
>>>>
>>>> http://bender.astro.sunysb.edu/random/test_0000.png
>>>>
>>>> and the script:
>>>>
>>>> http://bender.astro.sunysb.edu/random/vol_rotate.py
>>>>
>>>> any pointers are appreciated.
>>>>
>>>> Mike
>>>> --
>>>> Michael Zingale
>>>> Associate Professor
>>>>
>>>> Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY
>>>> 11794-3800
>>>> *phone*:  631-632-8225
>>>> *e-mail*: Michael.Zingale at stonybrook.edu
>>>> *web*: http://www.astro.sunysb.edu/mzingale
>>>>
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>>>>
>>>>
>>>
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>>
>>
>> --
>> Michael Zingale
>> Associate Professor
>>
>> Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY
>> 11794-3800
>> *phone*:  631-632-8225
>> *e-mail*: Michael.Zingale at stonybrook.edu
>> *web*: http://www.astro.sunysb.edu/mzingale
>>
>
>
>
> --
> Michael Zingale
> Associate Professor
>
> Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY
> 11794-3800
> *phone*:  631-632-8225
> *e-mail*: Michael.Zingale at stonybrook.edu
> *web*: http://www.astro.sunysb.edu/mzingale
>
> _______________________________________________
> yt-users mailing list
> yt-users at lists.spacepope.org
> http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
>
>
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