change each line color as a rainbow python
from matplotlib.pyplot import cm
import numpy as np
#variable n below should be number of curves to plot
#version 1:
color=cm.rainbow(np.linspace(0,1,n))
for i,c in zip(range(n),color):
plt.plot(x, y,c=c)
#or version 2:
color=iter(cm.rainbow(np.linspace(0,1,n)))
for i in range(n):
c=next(color)
plt.plot(x, y,c=c)