Question

I just discovered pyplot.scatter and have been playing with it a bit. I’m having trouble interpreting my results due to the coloring. For example, given my 3 (a,b) sized data arrays dataX, dataY, and dataMag:

import pyplot as plt
import numpy as np

plt.scatter(x=dataX.flat, y=dataY.flat, vmin=np.min(dataMag),
            vmax=np.max(dataMag), c=dataMag.flat, lw=1, s=1)
plt.show()

It would be really helpful if there was a way to set the low values in dataMag (i.e. 0) to white and have the colors gradually increase to the maximum color of black, or red, or whatever i don’t care. Is there a way to do this?

Thanks in advance!

Answer 1

I think you are looking for the kwarg cmap.

 plt.scatter(...,cmap='hot')

Taken from the scipy cookbook:

from pylab import *
from numpy import outer
rc('text', usetex=False)
a=outer(arange(0,1,0.01),ones(10))
figure(figsize=(10,5))
subplots_adjust(top=0.8,bottom=0.05,left=0.01,right=0.99)
maps=[m for m in cm.datad if not m.endswith("_r") ]
maps.sort()
l=len(maps)+1
for i, m in enumerate(maps):
    subplot(1,l,i+1)
    axis("off")
    imshow(a,aspect='auto',cmap=get_cmap(m),origin="lower")
    title(m,rotation=90,fontsize=10)

well generate a figure with all the color maps available with your installation. The name with ‘_r’ appeded on the end will give you the same map, with the colors in the opposite direction.

It is also possible to define your own custom color maps