matplotlib---Path

import matplotlib.pyplot as plt
from matplotlib.path import Path
import matplotlib.patches as patches

verts = [
    (0., 0.),  # left, bottom
    (0., 1.),  # left, top
    (1., 1.),  # right, top
    (1., 0.),  # right, bottom
    (0., 0.),  # ignored
]
codes = [Path.MOVETO,
         Path.LINETO,
         Path.LINETO,
         Path.LINETO,
         Path.CLOSEPOLY,
         ]
path = Path(verts, codes)
fig = plt.figure()
ax = fig.add_subplot(111)
patch = patches.PathPatch(path)
ax.add_patch(patch)
ax.set_xlim(-2, 2)
ax.set_ylim(-2, 2)
plt.show()