Pawel Janowski, on 2010-12-23 10:09, wrote: > Hi Pavel, > > Thanks for your help. Matplotlib seems to be a really cool tool. Your > response almost answered my question. What I want is for the 3D plot to be > 2D. I mean the z-axis can only take on 5 discreet values so I don't want to > visualize 3 dimensions but just two with the data points colored five > different colors depending on the z value.
Pawel,
(I'm replying back to the list, so that others may benefit -
hello there, search engine visitors from the future!)
In that case, you can either follow Goya's suggestion - if you
only want to draw points. scatter will actually rescale the color
values you give to whatever colormap you're using - and for your
case, with just five z values in range(1,6), I found a slight
tweak to the 'hsv' colormap does the trick.
from numpy.random import rand, randint
import matplotlib.pyplot as plt
x,y = rand(2,100)
z = randint(1,6,100)
plt.scatter(x,y,c=z, vmin=-1, cmap=plt.get_cmap('hsv'))
You can see the built-in colormaps here:
http://matplotlib.sourceforge.net/examples/pylab_examples/show_colormaps.html
and as Goyo showed, it's pretty easy to make a new one.
If you want more control, such as changing the shape of the
marker, not just the color, or if there's some order to your points
that you want to also see (for example, draw lines between points
of the same z value) - you can use a boolean mask.
from numpy.random import rand, randint
import matplotlib.pyplot as plt
x,y = rand(2,100)
z = randint(1,6,100)
for i,c,m in zip(range(1,6),'rgbmk', 'odp*s'):
mask = z==i
plt.plot(x[mask],y[mask], color=c, marker=m)
hope that helps,
--
Paul Ivanov
314 address only used for lists, off-list direct email at:
http://pirsquared.org | GPG/PGP key id: 0x0F3E28F7
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