Re: [Matplotlib-users] Best way to cycle through numpy images using scroll?

[Tom D. <tdi...@ph...>]

Here is how am solving this problem.  It isn't terribly fast either, but 
it works for me.  I wrote something with pygame that was faster, but it 
had its own set of problems.

Tom

---

import numpy as np
import pylab

class plotter:
     def __init__(self, im, i=0):
         self.im = im
         self.i = i
         self.vmin = im.min()
         self.vmax = im.max()
         self.fig = pylab.figure()
         pylab.gray()
         self.ax = self.fig.add_subplot(111)
         self.draw()
         self.fig.canvas.mpl_connect('key_press_event',self.key)

     def draw(self):
         if self.im.ndim is 2:
             im = self.im
         if self.im.ndim is 3:
             im = self.im[...,self.i]
             self.ax.set_title('image {0}'.format(self.i))

         pylab.show()

         self.ax.imshow(im, vmin=self.vmin, vmax=self.vmax, 
interpolation=None)


     def key(self, event):
         old_i = self.i
         if event.key=='right':
             self.i = min(self.im.shape[2]-1, self.i+1)
         elif event.key == 'left':
             self.i = max(0, self.i-1)
         if old_i != self.i or old_j != self.j:
             self.draw()
             self.fig.canvas.draw()


def show(im, i=0):
     plotter(im, i)


On 08/17/2011 01:26 PM, Keith Hughitt wrote:
> I'm also looking into a similar issue, and would be interested to see
> what approaches others have taken.
>
> Has anyone found a good framework-independent solution?
>
> Keith
>
> On Wed, Aug 10, 2011 at 5:15 PM, David Just <Jus...@ma...
> <mailto:Jus...@ma...>> wrote:
>
>     I have an array of images stored as an array of numpy arrays.   I
>     need to be able to efficiently scroll through that set of images.
>        My first attempt at doing this goes something like this:
>
>     --init--
>
>     self.ax <http://self.ax> = pyplot.imshow(imgdta[0],
>     interpolation='spline36', cmap=cm.gray, picker=True)      # draw the
>     plot @UndefinedVariable
>              pyplot.axes().set_axis_off()
>              self.fig = self.ax.get_figure()
>              self.canvas = FigureCanvasGTKAgg(self.fig)
>
>     --onscroll--
>              self.ax.set_array(imdta[n]) # 0 < n < num_images
>              self.canvas.draw()
>
>
>     This method of changing the image data does not seem to be very
>     preferment.  It takes ~.25 seconds to go from one image to the next.
>        Can anybody suggest a faster way?  This also ends up in a canvas
>     that’s much larger than I need, is there a better way to define my
>     view area?
>
>
>     Thank you,
>     Dave.
>
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