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:
http://www.scipy.org/Mailing_Lists
If you are using a particular plotting package like matplotlib, you will want to
ask your plotting questions on their mailing lists. E.g.
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
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().
http://matplotlib.sourceforge.net/api/pyplot_api.html#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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