matplotlib-users Mailing List for matplotlib

On Mon, Jan 23, 2012 at 3:19 PM, Paul Ivanov <piv...@gm...> wrote:

> Paul Ivanov, on 2012-01-23 13:07,  wrote:
> > the quick and dirty way to get close to what you want is to add
> > an alpha value to the lines you're already plotting. Here's a
> > small example:
> >
> >   x = np.arange(0,3,.01)
> >   y = np.sin(x**2)
> >   all_x,all_y = [],[]
> >   ax = plt.gca()
> >   for i in range(100):
> >       noisex = np.random.randn(1)*.04
> >       noisey = (np.random.randn(x.shape[0])*.2)**3
> >       ax.plot(x+noisex,y+noisey, color='b', alpha=.01)
> >       all_x.append(x+noisex)
> >       all_y.append(y+noisey)
> >
> > To get a heat diagram, as was suggested, you can use a 2d
> > histogram.
> >
> >   plt.figure()
> >   all_x =np.array(all_x)
> >   all_y = np.array(all_y)
> >   all_x.shape = all_y.shape = -1
> >   H, yedges, xedges = np.histogram2d(all_y, all_x, bins=100)
> >   extent = [xedges[0], xedges[-1], yedges[-1], yedges[0]]
> >   ax = plt.gca()
> >   plt.hot()
> >   ax.imshow(H, extent=extent, interpolation='nearest')
> >   ax.invert_yaxis()
>
> For completeness, attached is what the hexbin version of the same
> data looks like:
>
>   plt.hexbin(all_x, all_y)
>
> You may want to play with the 'bins' (for histogram2d) and
> 'griddata' (for hexbin) parameters to get the appropriate level
> of detail for the amount of data you have.
>
>

To get a proper count of the 2D bins that each curve crosses, you could
parameterize the curve by arclength and resample it use a small step size.
Or, you could linearly interpolate between the curve's discretized data
points using Bresenham's line algorithm.  The latter seemed like a
straightforward approach, so I wrote it up and added it to the SciPy
Cookbook:
    http://www.scipy.org/Cookbook/EyeDiagram

Warren

Newbie to using matplotlib

Is it possible to use wx and have a window with say 2 buttons on where when
clicking on either button a different graph will appear using a different
data set. Any examples?

Regards
Phil
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Le vendredi 03 février 2012 à 17:39 +0000, David Craig a écrit :
> sure how to get it to plot the outputs from specgram. I use 
> specgram as follows,
> Pxx, freqs, bins, im = plt.specgram(......)
> what am I trying imshow?? 

plt.specgram computes the spectrogram and when calls imshow to display
the resulting array into an image

Please tell the shape of Pxx, and try the following

import numpy as np
import matplotlib.pyplot as plt
a = np.empty((12000, 14400), dtype=float)
plt.imshow(a)
plt.show()

I noticed this a few years back, but left it aside because most of the
time I can live with it.  Recently I need to make a few plots
containing a few million points, and 4 pixels for a point is a
disaster.  So my question is why the pixel marker size is set at 4
pixels?  And is there anyway to change it to a single pixel?

Thanks,
Chris

On Friday, February 3, 2012, Jacob Biesinger <jak...@gm...>
wrote:
> Hi!
> In matplotlib's 3d plotting, the three corners of the 3d cube closest to
the camera are used as the axis and receive tick marks, labels, and a dark
black line. Is it possible to have the black line and ticks show
simultaneously on the 3 far corners at the top of the cube?
> For example, I'd like to have the top-left corner, top-right corner and
right side of this image be dark and include ticks, but not tick labels.
> http://dl.dropbox.com/u/1299034/fig_example.png
> Thanks!
>

Unfortunately, that level of customization is not in the design of mplot3d.
 It it possible that it may happen in future releases as I work to bring
mplot3d into feature-parity with regular axes, it won't happen soon.

Now, that doesn't mean that it is impossible to do right now, but it would
require hacking the axis3d.py file.  For each axis, a panel is drawn (which
is what you see now).  It is possible to simply have it plot a second
(transparent) panel on the far side with a black outline.  Next, there is a
loop that makes the ticks and the labels at the same time.  Just duplicate
that loop, but for the far edge and exclude the labels.

Sorry I can't be of more help right now, but I hope this info gets you
where you need to be.

Cheers,
Ben Root

Hi!

In matplotlib's 3d plotting, the three corners of the 3d cube closest to
the camera are used as the axis and receive tick marks, labels, and a dark
black line. Is it possible to have the black line and ticks show
simultaneously on the 3 far corners at the top of the cube?

For example, I'd like to have the top-left corner, top-right corner and
right side of this image be dark and include ticks, but not tick labels.

http://dl.dropbox.com/u/1299034/fig_example.png

Thanks!