Line with formatting

import matplotlib.pyplot as plt

x = [ 3,  4,   5,  6 ]
y = [ 23, 42, 10, 19 ]

#plt.plot(x, y, "b-")  # blue solid line
#plt.plot(x, y, "ro")  # red circles
#plt.plot(x, y, "gx")   # green x-es
plt.plot(x, y, "g--")   # green dashed line
plt.plot(x, y, "rD")   # red diamonds

#plt.show()
plt.savefig('line_with_formatting.png')

See the documentation of plot for a listing of styles.