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.
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 <jkly...@uvic.ca> 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 <kd5...@gmail.com> 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/
>
>
>
>
>
>
>
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> things parallel software development, from weekly thought leadership blogs
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conversation now. http://goparallel.sourceforge.net/
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