Re: [Matplotlib-users] Color Bar Limits

[Benjamin R. <ben...@ou...>]

::Looks again::

Ok, I see what you did here:

cmap = plt.get_cmap('rainbow_r’)
start=0.2
stop = 1.
colors = cmap(np.linspace(start, stop, cmap.N))
# Create a new colormap from those colors
color_map = LinearSegmentedColormap.from_list('Upper Half', colors)

I missed this part the first time through, noticing only the change to the
vmin. Yeah, I think that would work just fine. Sorry for the confusion.

Cheers!
Ben Root


On Thu, Apr 2, 2015 at 12:56 PM, Jody Klymak <jk...@uv...> wrote:

>
>
> On 2 Apr 2015, at  9:50 AM, Benjamin Root <ben...@ou...> wrote:
>
> No, that's not what he is asking for. John wants the norm to go from -1 to
> 4, but he wants the colorbar to display only the 0 to 4 portion. Your
> approach (setting vmin=0) would change the normalization and change the
> colors.
>
>
> Hmm, well his values go from 0 to 4, and he wants his colorbar to go from
> 0 to 4, but just over the last 4/5ths of the colormap.  I think I gave him
> what he wants.  But I guess he can decide!
>
> Cheers,   Jody
>
> The axes limits do not appear to be scaled by the values. They are set to
> (0, 1). So, the kludgy way would seem to be to set the xlimits to be (0.2,
> 1) (taking out a fifth of the colorbar, but the frame is still there...
>
> Ben Root
>
> On Thu, Apr 2, 2015 at 12:32 PM, Jody Klymak <jk...@uv...> wrote:
>
>> Hi John,
>>
>> I got this off stack exchange, apologies to the original contributor...
>>
>> Cheers,   Jody
>>
>>
>> import numpy as np
>> import matplotlib.pyplot as plt
>> from matplotlib.colors import LinearSegmentedColormap
>>
>> x = np.arange(100)
>> y = np.random.rand(100)
>> z = 4 * np.random.rand(100)
>>
>> cmap = plt.get_cmap('rainbow_r’)
>> start=0.2
>> stop = 1.
>> colors = cmap(np.linspace(start, stop, cmap.N))
>> # Create a new colormap from those colors
>> color_map = LinearSegmentedColormap.from_list('Upper Half', colors)
>>
>> fig = plt.figure(figsize=(12,9))
>> ax1 = plt.subplot(111)
>> sc = ax1.scatter(x, y, c=z, s=50, cmap=color_map, vmin=0, vmax=4)
>>
>> position=fig.add_axes([0.37, 0.16, 0.5, 0.02])
>> cb = fig.colorbar(sc, cax=position, orientation='horizontal',
>> drawedges=False)
>> cb.set_label('Z-Colors', fontsize=14)
>>
>> # I tried this after talking with Ben Root, but it
>> # results in some odd behavior
>> # cb.ax.set_xlim(0,4)
>>
>> plt.show()
>>
>>
>>
>> On 2 Apr 2015, at  5:47 AM, John Leeman <kd...@gm...> wrote:
>>
>> Hi all,
>>
>> I’m plotting some scatter points colored by a third variable, but want to
>> use a limited subset of a colormap. In the example below, the color axis
>> data ranges from 0-4, but I want to not use the red portion of the bar.
>> Doing the first part is just accomplished by setting the vmin/vmax. But
>> when I plot a color bar I don’t want to show the colors and values for
>> anything below zero. Other than just white-boxing that part of the bar I’m
>> not sure how to do it. I tried a suggestion of setting the limit properties
>> of the bar axis attribute, but that results in the bar getting shrunk and
>> shifted (a very weird behavior). Any ideas?
>>
>> Thank you,
>>
>> John Leeman
>>
>> import numpy as np
>> import matplotlib.pyplot as plt
>>
>> x = np.arange(100)
>> y = np.random.rand(100)
>> z = 4 * np.random.rand(100)
>>
>> color_map = plt.get_cmap('rainbow_r')
>>
>> fig = plt.figure(figsize=(12,9))
>> ax1 = plt.subplot(111)
>> sc = ax1.scatter(x, y, c=z, s=50, cmap=color_map, vmin=-1, vmax=4)
>>
>> position=fig.add_axes([0.37, 0.16, 0.5, 0.02])
>> cb = fig.colorbar(sc, cax=position, orientation='horizontal',
>> drawedges=False)
>> cb.set_label('Z-Colors’, fontsize=14)
>>
>> # I tried this after talking with Ben Root, but it
>> # results in some odd behavior
>> # cb.ax.set_xlim(0,4)
>>
>> plt.show()
>> <Color_Bar.png>
>>
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>> --
>> Jody Klymak
>> http://web.uvic.ca/~jklymak/
>>
>>
>>
>>
>>
>>
>>
>> ------------------------------------------------------------------------------
>> Dive into the World of Parallel Programming The Go Parallel Website,
>> sponsored
>> by Intel and developed in partnership with Slashdot Media, is your hub
>> for all
>> things parallel software development, from weekly thought leadership
>> blogs to
>> news, videos, case studies, tutorials and more. Take a look and join the
>> conversation now. http://goparallel.sourceforge.net/
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>> Matplotlib-users mailing list
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>
> --
> Jody Klymak
> http://web.uvic.ca/~jklymak/
>
>
>
>
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>