python 2.7 - Matplotlib - Changing line color above/below hline -

i have line plot , 2 hlines, using different colors, , i'm filling areas main line crosses hlines color of hline. in addition that, i'd use same color main line in areas. in nutshell, current output:

desired output:

and relevant code i'm using:

lower, upper = 20, 80  self.indicatorplot.axhline(lower, color="red") self.indicatorplot.axhline(upper, color="green")  self.indicatorplot.plot(self.charttimes, self.indicatordata, color="blue")  self.indicatorplot.fill_between(self.charttimes, self.indicatordata, lower, where=(self.indicatordata <= lower), facecolor="red", interpolate=true) self.indicatorplot.fill_between(self.charttimes, self.indicatordata, upper, where=(self.indicatordata >= upper), facecolor="green", interpolate=true) 

in principle may split plot 3 parts, values above upper, values below lower , values in middle. in sense question has been asked , answered, e.g.

• python: possible change line color in plot if exceeds specific range?
• plot: color larger different color

those solutions work great if point density high enough, such lines end close enough threshold line.

in case have larger gaps not suited. hence give solution here, interpolates gaps such lines end @ threshold line.

import numpy np; np.random.seed(43) import matplotlib.pyplot plt  t = np.linspace(0,100,301) x = np.cumsum(np.random.randn(len(t)))  lower,upper = 0,8  fig, ax=plt.subplots()  ax.axhline(lower, color="crimson") ax.axhline(upper, color="limegreen")   def insertzeros(t, x, zero=0):     ta = []     positive = (x-zero) > 0     ti = np.where(np.bitwise_xor(positive[1:], positive[:-1]))[0]     in ti:         y_ = np.sort(x[i:i+2])         z_ = t[i:i+2][np.argsort(x[i:i+2])]         t_ = np.interp(zero, y_, z_)         ta.append( t_ )     tnew = np.append( t, np.array(ta) )     xnew = np.append( x, np.ones(len(ta))*zero )     xnew = xnew[tnew.argsort()]     tnew = np.sort(tnew)     return tnew, xnew  t1,x1 = insertzeros(t,x, zero=lower) t1,x1 = insertzeros(t1,x1, zero=upper)  xm = np.copy(x1) xm[(x1 < lower) | (x1 > upper)] = np.nan         ax.plot(t1,xm, color="c0")  xl = np.copy(x1) xl[(x1 > lower)] = np.nan         ax.plot(t1,xl, color="crimson") # xu = np.copy(x1) xu[(xu < upper)] = np.nan         ax.plot(t1,xu, color="limegreen")  ax.fill_between(t, x, lower, where=(x <= lower), facecolor="crimson", interpolate=true, alpha=0.5) ax.fill_between(t, x, upper, where=(x >= upper), facecolor="limegreen", interpolate=true, alpha=0.5)   plt.show()