matplotlib bar plot only top line code example
Example: matplotlib change bar color under threshold
import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
N = 5
ind = np.arange(N)
width = 0.5
vals = [1,2,3,4,5]
colors = ['r','b','b','b','b']
ax.barh(ind, vals, width, color=colors)
plt.show()