Implementing horizon charts in matplotlib

Question

I\'m trying to implement horizon charts in matplotlib (see: http://square.github.com/cubism/)

The basic idea is that you display a time series in narrow aspect ratio, an

Answer 1

I actually do not know, why yours is not working, because on my computer it works fine. But since I am really interested in this plotting, I tried to implement it on my own without all this fancy twinx stuff.

I just plot these areas on top of eachother, since this is actually the great thing about the plot. Thus I do not need to adjust the alpha, they just add up.

import numpy as np
from matplotlib.pyplot import *

def layer(y,height):
    neg=0.0;pos=0.0
    if y>0:
        if y-height>=0:
            pos=height
            y-= pos
        else : 
            pos = y
    elif y<0:
        if y+height<=0:
            neg=height
            y += neg
        else : 
            neg = -y
    return pos,neg

def horizonPlot(x,y,height=50.0,colors=['CornflowerBlue','DarkGreen']):
    alpha = .10
    vlayer = np.vectorize(layer)
    while (y != 0).any():
        l = vlayer(y,height)
        y -= l[0];y += l[1]
        fill_between(x,0,l[0],color=colors[0], alpha=alpha)
        fill_between(x,height-l[1],height,color=colors[1], alpha=alpha)

def main():
    x = np.linspace(0, np.pi*4, 137)
    y = (2*np.random.normal(size=137) + x**2)
    xx = np.hstack([-1*x[::-1], x])
    yy = np.hstack([-1*y[::-1], y])
    horizonPlot(xx,yy)
    show()

This looks like the following on my machine. Hope it works on yours, but I just use basic plotting methods.