extensive scatter plot

Robert Kern robert.kern at gmail.com
Wed Nov 24 17:02:29 CET 2010

On 11/24/10 9:12 AM, Johannes Korn wrote:
> Hi,
> I would like to produce a scatter plot with roughly 200 mio points.
> Because the points are so numerous I rather need a point density plot.
> I use numpy. Right now I loop over the individual data points and make a
> where query on a meshgrid.
> ind = where((x_grid == x_points[i])&  (y_grid == y_points[i]) )
> counter_grid[ind] += 1
> This is really slow. I'm sure there's a better solution already out there.
> Kind regards!

You will want to ask numpy questions on the numpy mailing list:


If you are using a particular plotting package like matplotlib, you will want to 
ask your plotting questions on their mailing lists. E.g.


If you are doing your own plotting, you will want to use the numpy.histogram2d() 
function to make a 2D histogram that can be plotted using a colormapped image. 
If you are using matplotlib, try matplotlib.pyplot.hexbin().


Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

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