python-shapely/docs/code/linearring.py at master · johanvdw/python-shapely · GitHub

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from matplotlib import pyplot
from shapely.geometry.polygon import LinearRing

from figures import SIZE

COLOR = {
    True:  '#6699cc',
    False: '#ff3333'
    }

def v_color(ob):
    return COLOR[ob.is_valid]

def plot_coords(ax, ob):
    x, y = ob.xy
    ax.plot(x, y, 'o', color='#999999', zorder=1)

def plot_line(ax, ob):
    x, y = ob.xy
    ax.plot(x, y, color=v_color(ob), alpha=0.7, linewidth=3, solid_capstyle='round', zorder=2)

fig = pyplot.figure(1, figsize=SIZE, dpi=90)

# 1: valid ring
ax = fig.add_subplot(121)
ring = LinearRing([(0, 0), (0, 2), (1, 1), (2, 2), (2, 0), (1, 0.8), (0, 0)])

plot_coords(ax, ring)
plot_line(ax, ring)

ax.set_title('a) valid')

xrange = [-1, 3]
yrange = [-1, 3]
ax.set_xlim(*xrange)
ax.set_xticks(range(*xrange) + [xrange[-1]])
ax.set_ylim(*yrange)
ax.set_yticks(range(*yrange) + [yrange[-1]])
ax.set_aspect(1)

#2: invalid self-touching ring
ax = fig.add_subplot(122)
ring2 = LinearRing([(0, 0), (0, 2), (1, 1), (2, 2), (2, 0), (1, 1), (0, 0)])

plot_coords(ax, ring2)
plot_line(ax, ring2)

ax.set_title('b) invalid')

xrange = [-1, 3]
yrange = [-1, 3]
ax.set_xlim(*xrange)
ax.set_xticks(range(*xrange) + [xrange[-1]])
ax.set_ylim(*yrange)
ax.set_yticks(range(*yrange) + [yrange[-1]])
ax.set_aspect(1)

pyplot.show()