How could I add trendline to a dot graph drawn using matplotlib.scatter?
martinenzinger
as explained here
With help from numpy one can calculate for example a linear fitting.
# plot the data itself
pylab.plot(x,y,'o')
# calc the trendline
z = numpy.polyfit(x, y, 1)
p = numpy.poly1d(z)
pylab.plot(x,p(x),"r--")
# the line equation:
print "y=%.6fx+(%.6f)"%(z[0],z[1])
来源：https://stackoverflow.com/questions/26447191/how-to-add-trendline-in-python-matplotlib-dot-scatter-graphs