matplotlib-users Mailing List for matplotlib

On Wed, Jun 22, 2011 at 9:15 AM, John Hunter <jd...@gm...> wrote:
> On Wed, Jun 22, 2011 at 8:30 AM, Michael Droettboom <md...@st...>
> wrote:
> > matplotlib doesn't currently support gradients. Patches welcome! :)
> It's
> > probably a lot of work to get it working across all backends, but
> following
> > the pattern of how hatches are handled now would probably be a good
> guide.
>
> There is however, the gradient hack, eg
>
> http://matplotlib.sourceforge.net/examples/pylab_examples/gradient_bar.html
>
> JDH
>
>
There are also some neat tricks you can do with Agg filters. Here is an
example:
http://matplotlib.sourceforge.net/examples/pylab_examples/demo_agg_filter.html
Ben Root

On Wed, Jun 22, 2011 at 8:30 AM, Michael Droettboom <md...@st...> wrote:
> matplotlib doesn't currently support gradients. Patches welcome! :) It's
> probably a lot of work to get it working across all backends, but following
> the pattern of how hatches are handled now would probably be a good guide.
There is however, the gradient hack, eg
http://matplotlib.sourceforge.net/examples/pylab_examples/gradient_bar.html
JDH

matplotlib doesn't currently support gradients. Patches welcome! :) 
It's probably a lot of work to get it working across all backends, but 
following the pattern of how hatches are handled now would probably be a 
good guide.
Mike
On 06/21/2011 07:18 PM, Paul Menzel wrote:
> Dear Matplotlib folks,
>
>
> is it possible in Matplotlib to add eye candy or gimmicks to the plots
> like fading? For example if I want to just show a subpart(?) of a plot
> this would like "cool". (I am pretty sure that opinions differ if such
> things are useful or not, but please leave this out of the discussion.)
>
> It looks like PGF/TikZ supports such things (manual [1], page 206) and
> therefore I am wondering if Matplotlib can do this too?
>
>
> Thanks,
>
> Paul
>
>
> [1] http://www.ctan.org/tex-archive/graphics/pgf/base/doc/generic/pgf/pgfmanual.pdf
>
>
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-- 
Michael Droettboom
Science Software Branch
Space Telescope Science Institute
Baltimore, Maryland, USA

Hello,
i have a small problem sharing axes with twinned subplots.
Here is a code snippet:
ax = fig.add_subplot(212, sharex = bx)
ax.plot() 
grid()
cx = ax.twinx()
cx.plot() 
The problem is, that both axis are independent. So on the left side, the tick 
steps are 0.05 and on the right side 0.1. 
The gridlines of the ax plot also do not match to the tickmarks on the right 
side. How can i fix that?
Greeting 
Matthias

Am Dienstag, den 21.06.2011, 19:17 -0400 schrieb jos...@gm...:
> On Tue, Jun 21, 2011 at 5:25 PM, Paul Menzel wrote:
> > Am Dienstag, den 21.06.2011, 09:43 -0400 schrieb jos...@gm...:
> >> On Tue, Jun 21, 2011 at 8:47 AM, Paul Menzel wrote:
> >
> >> > I want to plot all paths of a simple random walk and wrote the following
> >> > recursive program based on the Path tutorial [1].
> >> >
> >> > import matplotlib.pyplot as plt
> >> > from matplotlib.path import Path
> >> > import matplotlib.patches as patches
> >> >
> >> > def draw(a, b, c, d):
> >> > verts = [
> >> > (a, b),
> >> > (c, d),
> >> > (0, 0),
> >> > ]
> >> >
> >> > codes = [
> >> > Path.MOVETO,
> >> > Path.LINETO,
> >> > Path.CLOSEPOLY
> >> > ]
> >> >
> >> > path = Path(verts, codes)
> >> > patch = patches.PathPatch(path)
> >> > ax.add_patch(patch)
> >> >
> >> > def irrpfad(a, b):
> >> > if a < length:
> >> > draw(a, b, a + 1., b + 1.)
> >> > draw(a, b, a + 1., b - 1.)
> >> > irrpfad(a + 1, b + 1)
> >> > irrpfad(a + 1, b - 1)
> >> >
> >> >
> >> > length = 5 # 20 not possible to run
> >> >
> >> > fig = plt.figure()
> >> > ax = fig.add_subplot(111)
> >> > irrpfad(0, 0)
> >> > ax.set_xlim(0,length)
> >> > ax.set_ylim(-length,length)
> >> > plt.show()
> >> >
> >> > Using 20 for `length` stalls my system and the memory used seems to be
> >> > over 1 GB. I guess this is what you guess using something recursive.
> >> > What optimizations are there. I am drawing each line after another so
> >> > probably too many separate paths instead of one. Being a Python noob I
> >> > do not know if I can append something to a path. Looking at the API
> >> > documentation [2] I did not see such a method.
> >> >
> >> > Being also new to Matplotlib I may have also overlooked more appropriate
> >> > methods/classes.
> >> >
> >> > So to summarize my message,
> >> >
> >> > 1. How can I add lines to a path?
> >> > 2. Are recursive functions bad in Python/Matplotlib?
> >> > 3. Are there better approaches?
> >>
> >> I'm not sure what you are trying to show, but my impression is that you are
> >> just producing the grid between integers (move up,down),
> >
> > Yeah, that is about right [1].
> >
> >> and paths will not show up because the lines are all on top of each other.
> >
> > That is not true. My program displays everything correctly when using
> > for example `length = 5`.
> >
> >> The number of all paths looks very large to me and even without matplotlib
> >> overhead, this might soon run into problems.
> >
> > That is what thought too.
> >
> >> for example;
> >> for length= 15; I get 65534 moves in the random walks, but only 240 unique moves
> >> for length= 20; I get 2097150 moves in the random walks, but only 420 unique moves
> >> plotting only unique moves is fast (count of moves might work to color the
> >> amount of traffic on each move)
> >
> > I am sorry, I think that in my program no section is drawn more than
> > once.
> 
> each append below corresponds to one call to your draw function
> 
> Do you want to draw all possible routes, or the road network?
I am sorry. I now do understand your previous sentences correctly. Yes I
am aware that patches overlap and I only need to draw the road network.
> I only see the road network in the plot
Yes that is correct and intended.
> (and partially the traffic density with alpha<1).
Nice suggestion. Thank you.
> >> rw_moves = []
> >> def irrpfad2(a, b):
> >> if a < length:
> >> rw_moves.append((a, b, a + 1, b + 1))
> >> rw_moves.append((a, b, a + 1, b - 1))
> >> irrpfad2(a + 1, b + 1)
> >> irrpfad2(a + 1, b - 1)
> >>
> >> length = 20 # 20 not possible to run
> >> irrpfad2(0, 0)
> >
> > Thank you for the example, but now I need to somehow also add the codes
> > to be able to pass this to Path.
> >
> >> I don't know any answer to the matplotlib specific part
> >
> > Thank you for your other answers.
> >
> >> > Please find the source also attached. I am using python-matplotlib
> >> > 1.0.1-2 from Debian Sid/unstable.
Thanks,
Paul
> >> > [1] http://matplotlib.sourceforge.net/users/path_tutorial.html
> >> > [2] http://matplotlib.sourceforge.net/api/path_api.html#matplotlib.path.Path
> > [3] https://secure.wikimedia.org/wikipedia/en/wiki/Random_walk