matplotlib-users Mailing List for matplotlib

On Tue, May 10, 2011 at 9:25 AM, Jonathan Slavin <js...@cf...>wrote:
> Hi,
>
> I would like to create a plot with a series of parallel 2-D slices in
> order to illustrate 3-D data. I got excited when I saw the example of
> translucent bar plots, which is similiar in some ways to what I had in
> mind. But it seems that there is no imshow method in Axes3D. How hard
> would that be to add? (By the way, I do know about mayavi and have used
> it, but there are things about it that make it somewhat difficult to
> work with.)
>
> Jon
>
imshow() and friends work a little bit differently from the other plotting
commands. Unlike the other plotting functions, imshow() does not return any
Collection objects, rather it returns an AxesImage object. Most of the
other functions are merely wrappers around their 2D equivalent with a few
extra keyword arguments and a 2D to 3D converter call for the collection
objects returned. In order to support imshow() in Axes3D, a 3D version of
the AxesImage object will need to be made and should be able to be created
from an existing 2D version.
If someone wants to create a 3D version of AxesImage and add it to art3d.py,
I would be more than happy to take the patch. But at this time, I am too
unfamiliar with AxesImage objects and am more focused on fixing the current
feature-set.
Ben Root

Hi,
I would like to create a plot with a series of parallel 2-D slices in
order to illustrate 3-D data. I got excited when I saw the example of
translucent bar plots, which is similiar in some ways to what I had in
mind. But it seems that there is no imshow method in Axes3D. How hard
would that be to add? (By the way, I do know about mayavi and have used
it, but there are things about it that make it somewhat difficult to
work with.)
Jon
-- 
______________________________________________________________
Jonathan D. Slavin Harvard-Smithsonian CfA
js...@cf... 60 Garden Street, MS 83
phone: (617) 496-7981 Cambridge, MA 02138-1516
 cell: (781) 363-0035 USA
______________________________________________________________

Hi, I like this, too.
However, I don't understand why it works at all. Usually, when I apply
a colormap, I need to take care about the scaling myself, i.e. divide
the range up into the number of elements to plot:
import pylab as pl
import matplotlib.cm as cm
xval = pl.arange(0, 20, 0.2)
n = 256
for i in range(n):
# pl.plot(xval, pl.sin(xval)+i, c=cm.hot(i), lw=5)
 pl.plot(xval, pl.sin(xval)+i, c=cm.hot(1.*i/n), lw=5)
Can anyone tell me why this is not necessary here but essential for
example here:
for i,infile in enumerate(infiles):
 ## title for plot
 tname = os.path.splitext(infile)[0]
 ## read data
 f = FileHelpers.BlockedFile(infile)
 alldata = scipy.array([[],[]])
 for ii in ['+', '2', 'x', '1']: # use for markers, too
# for ii in [4,3,2,1]: # use for markers, too
 try:
 f.next_block()
 data = scipy.loadtxt(f).T
 alldata = scipy.concatenate((alldata, data), axis=1)
# ax.plot(data[0],data[1], '%s'%ii,
color=cm.hot(1.*i/len(infiles)), mew=1.5 )
 ax.plot(data[0],data[1], '%s'%ii, c=cm.hot(i), mew=1.5 )
 except Exception, e:
 print e
 break
Thanks in advance,
Daniel
>> I have found a simple and better way. One can chose from colors from a
>> color
>> map:
>>
>> >>import pylab as pl
>> >>import matplotlib.cm as cm
>> >>xval = pl.arange(0, 20, 0.2)
>> >>for i in range(256):
>>   ... pl.plot(xval, pl.sin(xval)+i, c=cm.hot(i), lw=5)
>>
>> This one if, for instance, picking from a color map called "hot". If one
>> wants to the colors to fade away, or darken, the "alpha" option can be
>> utilized or another color map in which colors darken or fade into another
>> color.
>>
>> There is no need for a long sophisticated script.

On Mon, May 9, 2011 at 5:11 PM, Pythonified <net...@gm...>wrote:
>
>
> Pythonified wrote:
> >
> > I have been trying to assign different colors for each line I plot, where
> > the colors are incrementally darkened (or lightened), or selected from a
> > colorbar (e.g. rainbow).
> >
> > Any ideas?
> >
>
> I have found a simple and better way. One can chose from colors from a
> color
> map:
>
> >>import pylab as pl
> >>import matplotlib.cm as cm
> >>xval = pl.arange(0, 20, 0.2)
> >>for i in range(256):
> ... pl.plot(xval, pl.sin(xval)+i, c=cm.hot(i), lw=5)
>
> This one if, for instance, picking from a color map called "hot". If one
> wants to the colors to fade away, or darken, the "alpha" option can be
> utilized or another color map in which colors darken or fade into another
> color.
>
> There is no need for a long sophisticated script.
>
> Enjoy,
> Pythonified
>
Nice trick. This can go into the gallery or somewhere else in scipy
cookbook.
-- 
Gökhan