matplotlib-users

[Matplotlib-users] a bunch of extra colormaps

[Jeff W. <js...@fa...>]

I've created matplotlib colormaps from all the color tables at 
http://colorbrewer.org, and 
http://geography.uoregon.edu/datagraphics/color_scales.htm.  You can 
grab them at 
http://www.cdc.noaa.gov/people/jeffrey.s.whitaker/python/extracmaps.py.gz.  
Also included are the Generic Mapping Tools colormaps (at least the ones 
that are different from the built in mpl colormaps), for a total of 60.  
You can just paste the contents of that file into cm.py just above the 
"def get_cmap" line (although this will not make them available via 
pylab calls like 'jet()' and 'hot()'). To get a quick view of what the 
colormaps look like, I use this little script:

import matplotlib.cm as cm
import pylab as p
names = cm.datad.keys()
print len(names),'total color maps'
def plot_colorbar(cmapname,nsteps=None):
    colormap = cm.__dict__[cmapname]
    fig=p.figure(figsize=(8,1))
    ax = fig.add_axes([0.05,0.05,0.9,0.70])
    if nsteps == None:
        nsteps = colormap.N+1
    clevs = p.linspace(0,1,nsteps+1)
    C = p.array([clevs,clevs])
    X,Y = p.meshgrid(clevs,[0,1])
    levs,coll = ax.contourf(C, Y, X, nsteps-1, cmap=colormap)
    ax.set_xticks([])
    ax.set_yticks([])
    p.title(cmapname)
    p.show()
if __name__ == "__main__":
    cmapname = raw_input('color map name:')
    if cmapname not in names:
        raise KeyError, 'invalid colormap name, valid names are 
'+repr(names)
    plot_colorbar(cmapname)

Enjoy!


-Jeff

-- 
Jeffrey S. Whitaker         Phone  : (303)497-6313
Meteorologist               FAX    : (303)497-6449
NOAA/OAR/CDC  R/CDC1        Email  : Jef...@no...
325 Broadway                Office : Skaggs Research Cntr 1D-124
Boulder, CO, USA 80303-3328 Web    : http://tinyurl.com/5telg

Re: [Matplotlib-users] a bunch of extra colormaps

[Helge A. <he...@gm...>]

On 8/26/05, Jeff Whitaker <js...@fa...> wrote:
> "def get_cmap" line (although this will not make them available via
> pylab calls like 'jet()' and 'hot()'). To get a quick view of what the

this is great, and I think the matlab way with a function for each
color map pollutes the namespace too much. I humbly suggest a syntax
like
  colormap('hot')
or to give bluetones for values < 0, greenish and brown above:
  colormap('earth', zerolevel=3D0.0)
etc. for pylab

Helge

Re: [Matplotlib-users] a bunch of extra colormaps

[Vidar G. <vid...@37...>]

===== Original message from Jeff Whitaker | Thu, 25 Aug 2005:
> I've created matplotlib colormaps from all the color tables at 
> http://colorbrewer.org, and 
> http://geography.uoregon.edu/datagraphics/color_scales.htm

thanks for providing this,
i hope this will be included in the matplotlib distribution,
along with your script for previewing and listing all colormaps?
(see modification of original code below.)


i would like to mention another archive of color gradients,
http://cpt-city.org.uk/. two examples of color gradients
found here that i think might be useful for plotting data:

Nonlinear grays, e.g. gamma={1/3, 0.5, 0.8, 1.25, ..}
(human vision are more sensitive in the lighter range)
http://cpt-city.org.uk/tl/

Subtle close-to-grayscale gradients, like for instance the
sephia and cyanotype tinted monochrome colormaps found here:
http://cpt-city.org.uk/erj/multiple/


"""
   Usage: colormap-preview.py [cmapname]
   Adapted from original code by Jeff Whitaker
   http://sourceforge.net/mailarchive/message.php?msg_id=12764609
"""
import matplotlib.cm as cm
import pylab as p

def plot_colorbar(cmapname,nsteps=None):
   colormap = cm.__dict__[cmapname]
   fig=p.figure(figsize=(8,1))
   ax = fig.add_axes([0.05,0.05,0.9,0.70])
   if nsteps == None:
       nsteps = colormap.N+1
   clevs = p.linspace(0,1,nsteps+1)
   C = p.array([clevs,clevs])
   X,Y = p.meshgrid(clevs,[0,1])
   levs,coll = ax.contourf(C, Y, X, nsteps-1, cmap=colormap)
   ax.set_xticks([])
   ax.set_yticks([])
   p.title(cmapname)
   p.show()

if __name__ == "__main__":
   names = cm.datad.keys()
   import sys
   if len(sys.argv) > 1:
      cmapname = sys.argv[1]
   else:
      print len(names), 'total color maps'
      print sorted(names)
      cmapname = raw_input('color map name: ')

   if cmapname not in names:
       raise KeyError, 'invalid colormap name,' +\
                       ' valid names are '+repr(names)
   plot_colorbar(cmapname)

## end of Python code


-- 
Vidar Bronken Gundersen
 blogged: http://www.37mm.no/blog/ColorBrewer_schemes_for_Matplotlib.html

Re: [Matplotlib-users] a bunch of extra colormaps

[John H. <jdh...@ac...>]

>>>>> "Vidar" == Vidar Gundersen <vid...@37...> writes:

    Vidar> thanks for providing this, i hope this will be included in
    Vidar> the matplotlib distribution, along with your script for
    Vidar> previewing and listing all colormaps?  (see modification of
    Vidar> original code below.)

I haven't been able to find any licensing information for the color
scales at colorbrewer or http://geography.uoregon.edu/datagraphics .
Does anyone know what their license is, if any?

JDH

Re: [Matplotlib-users] a bunch of extra colormaps

[Jeff W. <js...@fa...>]

John Hunter wrote:

>>>>>>"Vidar" == Vidar Gundersen <vid...@37...> writes:
>>>>>>            
>>>>>>
>
>    Vidar> thanks for providing this, i hope this will be included in
>    Vidar> the matplotlib distribution, along with your script for
>    Vidar> previewing and listing all colormaps?  (see modification of
>    Vidar> original code below.)
>
>I haven't been able to find any licensing information for the color
>scales at colorbrewer or http://geography.uoregon.edu/datagraphics .
>Does anyone know what their license is, if any?
>
>JDH
>
>  
>
John: Colorbrewer uses an apache-style license 
(http://www.personal.psu.edu/faculty/c/a/cab38/ColorBrewer/ColorBrewer_updates.html).  
I don't know about the DataGraphics color schemes.

-Jeff

-- 
Jeffrey S. Whitaker         Phone : (303)497-6313
NOAA/OAR/CDC  R/CDC1        FAX   : (303)497-6449
325 Broadway                Web   : http://www.cdc.noaa.gov/~jsw
Boulder, CO, USA 80305-3328 Office: Skaggs Research Cntr 1D-124