Re: [Matplotlib-users] How to shift colormap?
I learned some more about matplotlib colormaps from here:
http://www.scipy.org/Cookbook/Matplotlib/Show_colormaps
and tried to grasp cmap creation workflow.
Here is GMT_haxby:
_GMT_haxby_data = {
'blue': [
(0.0, 0.474509805441, 0.474509805441),
(0.0322580635548, 0.588235318661, 0.588235318661),
(0.0645161271095, 0.686274528503, 0.686274528503),
(0.0967741906643, 0.784313738346, 0.784313738346),
(0.129032254219, 0.831372559071, 0.831372559071),
(0.161290317774, 0.878431379795, 0.878431379795),
(0.193548381329, 0.941176474094, 0.941176474094),
(0.225806444883, 0.972549021244, 0.972549021244),
(0.258064508438, 1.0, 1.0),
(0.290322571993, 1.0, 1.0),
(0.322580635548, 1.0, 1.0),
(0.354838699102, 0.941176474094, 0.941176474094),
(0.387096762657, 0.882352948189, 0.882352948189),
(0.419354826212, 0.784313738346, 0.784313738346),
(0.451612889767, 0.68235296011, 0.68235296011),
(0.483870953321, 0.658823549747, 0.658823549747),
(0.516129016876, 0.635294139385, 0.635294139385),
(0.548387110233, 0.552941203117, 0.552941203117),
(0.580645143986, 0.474509805441, 0.474509805441),
(0.612903237343, 0.407843142748, 0.407843142748),
(0.645161271095, 0.341176480055, 0.341176480055),
(0.677419364452, 0.270588248968, 0.270588248968),
(0.709677398205, 0.29411765933, 0.29411765933),
(0.741935491562, 0.305882364511, 0.305882364511),
(0.774193525314, 0.352941185236, 0.352941185236),
(0.806451618671, 0.486274510622, 0.486274510622),
(0.838709652424, 0.61960786581, 0.61960786581),
(0.870967745781, 0.68235296011, 0.68235296011),
(0.903225779533, 0.768627464771, 0.768627464771),
(0.93548387289, 0.843137264252, 0.843137264252),
(0.967741906643, 0.921568632126, 0.921568632126),
(1.0, 1.0, 1.0)],
'green': [
(0.0, 0.0, 0.0),
(0.0322580635548, 0.0, 0.0),
(0.0645161271095, 0.0196078438312, 0.0196078438312),
(0.0967741906643, 0.0392156876624, 0.0392156876624),
(0.129032254219, 0.0980392172933, 0.0980392172933),
(0.161290317774, 0.156862750649, 0.156862750649),
(0.193548381329, 0.4000596, 0.4000596),
(0.225806444883, 0.505882382393, 0.505882382393),
(0.258064508438, 0.686274528503, 0.686274528503),
(0.290322571993, 0.745098054409, 0.745098054409),
(0.322580635548, 0.792156875134, 0.792156875134),
(0.354838699102, 0.882352948189, 0.882352948189),
(0.387096762657, 0.921568632126, 0.921568632126),
(0.419354826212, 0.921568632126, 0.921568632126),
(0.451612889767, 0.92549020052, 0.92549020052),
(0.483870953321, 0.960784316063, 0.960784316063),
(0.516129016876, 1.0, 1.0),
(0.548387110233, 0.960784316063, 0.960784316063),
(0.580645143986, 0.92549020052, 0.92549020052),
(0.612903237343, 0.843137264252, 0.843137264252),
(0.645161271095, 0.741176486015, 0.741176486015),
(0.677419364452, 0.627451002598, 0.627451002598),
(0.709677398205, 0.458823531866, 0.458823531866),
(0.741935491562, 0.313725501299, 0.313725501299),
(0.774193525314, 0.352941185236, 0.352941185236),
(0.806451618671, 0.486274510622, 0.486274510622),
(0.838709652424, 0.61960786581, 0.61960786581),
(0.870967745781, 0.701960802078, 0.701960802078),
(0.903225779533, 0.768627464771, 0.768627464771),
(0.93548387289, 0.843137264252, 0.843137264252),
(0.967741906643, 0.921568632126, 0.921568632126),
(1.0, 1.0, 1.0)],
'red': [
(0.0, 0.0392156876624, 0.0392156876624),
(0.0322580635548, 0.156862750649, 0.156862750649),
(0.0645161271095, 0.0784313753247, 0.0784313753247),
(0.0967741906643, 0.0, 0.0),
(0.129032254219, 0.0, 0.0),
(0.161290317774, 0.0, 0.0),
(0.193548381329, 0.101960785687, 0.101960785687),
(0.225806444883, 0.0509803928435, 0.0509803928435),
(0.258064508438, 0.0980392172933, 0.0980392172933),
(0.290322571993, 0.196078434587, 0.196078434587),
(0.322580635548, 0.26680574, 0.26680574),
(0.354838699102, 0.380392163992, 0.380392163992),
(0.387096762657, 0.415686279535, 0.415686279535),
(0.419354826212, 0.486274510622, 0.486274510622),
(0.451612889767, 0.541176497936, 0.541176497936),
(0.483870953321, 0.674509823322, 0.674509823322),
(0.516129016876, 0.803921580315, 0.803921580315),
(0.548387110233, 0.874509811401, 0.874509811401),
(0.580645143986, 0.941176474094, 0.941176474094),
(0.612903237343, 0.96862745285, 0.96862745285),
(0.645161271095, 1.0, 1.0),
(0.677419364452, 1.0, 1.0),
(0.709677398205, 0.956862747669, 0.956862747669),
(0.741935491562, 0.93337307, 0.93337307),
(0.774193525314, 1.0, 1.0),
(0.806451618671, 1.0, 1.0),
(0.838709652424, 1.0, 1.0),
(0.870967745781, 0.960784316063, 0.960784316063),
(0.903225779533, 1.0, 1.0),
(0.93548387289, 1.0, 1.0),
(0.967741906643, 1.0, 1.0),
(1.0, 1.0, 1.0)]}
Now imagine tweaking this map by hand, i.e. lower 0 value (~ 2/3 from whole
cmap in example) from orange to green-blue without ruining it totally
So I want to ask this question differently: Is there some tool (Inkscape,
CorelDraw, Photoshop, ... anything) that would let me use GUI with some
sliders so that I can try adjust matplotlib colormap?
On Sun, Nov 6, 2011 at 9:58 PM, klo uo klo...@gmail.com wrote:
Like in Basemap examples:
Re: [Matplotlib-users] How to shift colormap?
Or are matplotlib colormaps compatible with any other programs? On Fri, Nov 11, 2011 at 4:19 PM, klo uo klo...@gmail.com wrote: So I want to ask this question differently: Is there some tool (Inkscape, CorelDraw, Photoshop, ... anything) that would let me use GUI with some sliders so that I can try adjust matplotlib colormap? -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] How to shift colormap?
I have this script that uses the matplotlib Slider object to control the
colormap of a histogram. This could be very close to what you want. Here is
the script:
### begin colormap_slider.py #
import math, copy
import numpy
from matplotlib import pyplot, colors, cm
from matplotlib.widgets import Slider
def cmap_powerlaw_adjust(cmap, a):
'''
returns a new colormap based on the one given
but adjusted via power-law:
newcmap = oldcmap**a
'''
if a 0.:
return cmap
cdict = copy.copy(cmap._segmentdata)
fn = lambda x : (x[0]**a, x[1], x[2])
for key in ('red','green','blue'):
cdict[key] = map(fn, cdict[key])
cdict[key].sort()
assert (cdict[key][0]0 or cdict[key][-1]1), \
Resulting indices extend out of the [0, 1] segment.
return colors.LinearSegmentedColormap('colormap',cdict,1024)
def cmap_center_adjust(cmap, center_ratio):
'''
returns a new colormap based on the one given
but adjusted so that the old center point higher
(0.5) or lower (0.5)
'''
if not (0. center_ratio) (center_ratio 1.):
return cmap
a = math.log(center_ratio) / math.log(0.5)
return cmap_powerlaw_adjust(cmap, a)
def cmap_center_point_adjust(cmap, range, center):
'''
converts center to a ratio between 0 and 1 of the
range given and calls cmap_center_adjust(). returns
a new adjusted colormap accordingly
'''
if not ((range[0] center) and (center range[1])):
return cmap
return cmap_center_adjust(cmap,
abs(center - range[0]) / abs(range[1] - range[0]))
if __name__ == '__main__':
### create some 2D histogram-type data
def func3(x,y):
return (1- x/2 + x**5 + y**3)*numpy.exp(-x**2-y**2)
x = numpy.linspace(-3.0, 3.0, 60)
y = numpy.linspace(-3.0, 3.0, 60)
X,Y = numpy.meshgrid(x, y)
Z = func3(X, Y)
extent = [x[0],x[-1],y[0],y[-1]]
plotkwargs = {
'extent' : extent,
'origin' : 'lower',
'interpolation' : 'nearest',
'aspect' : 'auto'}
### interactively adjustable with a slider
fig = pyplot.figure(figsize=(6,4))
fig.subplots_adjust(top=0.8)
ax = fig.add_subplot(1,1,1)
cmap = cm.seismic
plt = ax.imshow(Z, cmap=cmap, **plotkwargs)
cb = fig.colorbar(plt, ax=ax)
axcmap = fig.add_axes([0.1, 0.85, 0.8, 0.05], axisbg='white')
scmap = Slider(axcmap, '', 0.0, 1.0, valinit=0.5)
def update(val):
cmapcenter = scmap.val
plt.set_cmap(cmap_center_adjust(cmap, cmapcenter))
scmap.on_changed(update)
pyplot.show()
### end colormap_slider.py ###
--
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Re: [Matplotlib-users] How to shift colormap?
Thanks Johann,
that is exactly what I asked for
I knew that matplotlib can do GUI tricks but I didn't felt skilled to go
there. Seeing you code it seems easy now, but it's always like that after
you see the solution :D
Cheers
On Fri, Nov 11, 2011 at 6:05 PM, johanngoetz jgo...@ucla.edu wrote:
I have this script that uses the matplotlib Slider object to control the
colormap of a histogram. This could be very close to what you want. Here is
the script:
### begin colormap_slider.py #
import math, copy
import numpy
from matplotlib import pyplot, colors, cm
from matplotlib.widgets import Slider
def cmap_powerlaw_adjust(cmap, a):
'''
returns a new colormap based on the one given
but adjusted via power-law:
newcmap = oldcmap**a
'''
if a 0.:
return cmap
cdict = copy.copy(cmap._segmentdata)
fn = lambda x : (x[0]**a, x[1], x[2])
for key in ('red','green','blue'):
cdict[key] = map(fn, cdict[key])
cdict[key].sort()
assert (cdict[key][0]0 or cdict[key][-1]1), \
Resulting indices extend out of the [0, 1] segment.
return colors.LinearSegmentedColormap('colormap',cdict,1024)
def cmap_center_adjust(cmap, center_ratio):
'''
returns a new colormap based on the one given
but adjusted so that the old center point higher
(0.5) or lower (0.5)
'''
if not (0. center_ratio) (center_ratio 1.):
return cmap
a = math.log(center_ratio) / math.log(0.5)
return cmap_powerlaw_adjust(cmap, a)
def cmap_center_point_adjust(cmap, range, center):
'''
converts center to a ratio between 0 and 1 of the
range given and calls cmap_center_adjust(). returns
a new adjusted colormap accordingly
'''
if not ((range[0] center) and (center range[1])):
return cmap
return cmap_center_adjust(cmap,
abs(center - range[0]) / abs(range[1] - range[0]))
if __name__ == '__main__':
### create some 2D histogram-type data
def func3(x,y):
return (1- x/2 + x**5 + y**3)*numpy.exp(-x**2-y**2)
x = numpy.linspace(-3.0, 3.0, 60)
y = numpy.linspace(-3.0, 3.0, 60)
X,Y = numpy.meshgrid(x, y)
Z = func3(X, Y)
extent = [x[0],x[-1],y[0],y[-1]]
plotkwargs = {
'extent' : extent,
'origin' : 'lower',
'interpolation' : 'nearest',
'aspect' : 'auto'}
### interactively adjustable with a slider
fig = pyplot.figure(figsize=(6,4))
fig.subplots_adjust(top=0.8)
ax = fig.add_subplot(1,1,1)
cmap = cm.seismic
plt = ax.imshow(Z, cmap=cmap, **plotkwargs)
cb = fig.colorbar(plt, ax=ax)
axcmap = fig.add_axes([0.1, 0.85, 0.8, 0.05], axisbg='white')
scmap = Slider(axcmap, '', 0.0, 1.0, valinit=0.5)
def update(val):
cmapcenter = scmap.val
plt.set_cmap(cmap_center_adjust(cmap, cmapcenter))
scmap.on_changed(update)
pyplot.show()
### end colormap_slider.py ###
--
View this message in context:
http://old.nabble.com/How-to-shift-colormap--tp32792283p32827012.html
Sent from the matplotlib - users mailing list archive at Nabble.com.
--
RSA(R) Conference 2012
Save $700 by Nov 18
Register now
http://p.sf.net/sfu/rsa-sfdev2dev1
___
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Matplotlib-users@lists.sourceforge.net
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--
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