[email protected] wrote:
> Hello,
>
> I'm trying to create a heat map from two lists of corresponding X and Y
> coordinates.
>
> I've tried both numpy.histogram2d() and pyplot.hexbin().
>
> The histogram I get back doesn't correspond to the points I gave it. It seems
> as if it's sorting each X and Y list and then eliminating some points, which
> would definitely not give me the coordinates I want. (Also, I want to be able
> to switch the origin to the upper-left corner, but I can't figure out how to
> do this with imshow().)
>
Histogram2d works fine for me, I use it more or less the same way you
do, so I can't help there.
You can specify the origin in imshow by saying:
plt.imshow(heatmap, extent=axesExtent, origin='upper')
> The hexbin graph does correspond to my original points, but rather than
> having hexagons of equal size, some are super thin and tiny. (I'd also like
> to fill in the entire graph with background color (I want the axes to extend
> beyond the data) - is there a way to do that?)
>
You can specify the bins in histogram2d to cover the whole screen (you
can also specify bins in hexbin, which should be similar):
xedges, yedges = linspace(0,1400,(1400/50)+1), linspace(0,600,(600/50)+1)
npy.histogram2d(xList, yList, bins=[xedges,yedges])
> Here's the code I wrote for the histogram and hexbin. Am I doing something
> wrong? I've attached three graphs - one is my coordinates as a scatter plot,
> one my histogram result, and the other the hexbin result.
>
> Thanks!
> ~Rachel
>
> def plotHistogram( coordsTuple ):
>
> plt.clf() # Clears any previous figure
>
> xList = coordsTuple[0]
> yList = coordsTuple[1]
>
> heatmap, xedges, yedges = npy.histogram2d(xList, yList)
> axesExtent = [0, xedges[-1], 0, yedges[-1]]
> plt.imshow(heatmap, extent = axesExtent)
>
> plt.title( "Heat Map of User Clicks" )
>
> name = raw_input("\nImage name and extension: ")
> plt.savefig(name)
>
>
> def plotHexbins( coordsTuple ):
>
> plt.clf() # Clears any previous figure
>
> xList = coordsTuple[0]
> yList = coordsTuple[1]
>
> plt.hexbin(xList, yList)
>
> plt.title( "Heat Map of User Clicks" )
>
> name = raw_input("\nImage name and extension: ")
> plt.savefig(name)
>
>
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