I have some points (X0, Y0), that define a polygon. X0, Y0 are 1D-arrays.
With plotly
polygon = go.Scatter(
x=X0,
y=Y0,
showlegend=False,
mode="lines",
fill="toself",
line=dict(color="LightSeaGreen", width=2),
)
The results looks not as expected, so I guess I need to somehow sort the points first.
Any idea how I could go about this?
(Ignore the red point.)
Adding to answer from @Tengis Using shapely you can construct a multipoint geometry and from that the convex hull. That's then simple to use in plotly
from plotly.subplots import make_subplots
import plotly.graph_objects as go
import shapely.geometry
import numpy as np
fig = make_subplots(1, 2, subplot_titles=("polygon0", "convex hull"))
X0 = [25, 50, 38, 40]
Y0 = [20, 40, 60, 25]
# 2D array of points that make up convex hull
convex_hull = np.array(
shapely.geometry.MultiPoint(
[xy for xy in zip(X0, Y0)]
).convex_hull.exterior.coords
)
polygon0 = go.Scatter(
x=X0,
y=Y0,
showlegend=False,
mode="lines",
fill="toself",
line=dict(color="LightSeaGreen", width=2),
)
polygon1 = go.Scatter(
x=convex_hull[:, 0],
y=convex_hull[:, 1],
showlegend=False,
mode="lines",
fill="toself",
line=dict(color="LightSeaGreen", width=2),
)
fig.add_trace(polygon0, row=1, col=1)
fig.add_trace(polygon1, row=1, col=2)
fig.update_xaxes(range=[20, 55])
fig.show()
The problem is in the order of your points. I have made an example with the same points but organized them differently (different positions in the array).
fig = make_subplots(1,3, subplot_titles=("polygon0", "polygon1", "polygon2"))
X0 = [25, 50, 38, 40]
Y0 = [20, 40, 60, 25]
X1 = [25, 38, 50, 40]
Y1 = [20, 60, 40, 25]
X2 = [25, 38, 50, 40, 25]
Y2 = [20, 60, 40, 25, 20]
polygon0 = go.Scatter(
x=X0,
y=Y0,
showlegend=False,
mode="lines",
fill='toself',
line=dict(color="LightSeaGreen", width=2)
)
polygon1 = go.Scatter(
x=X1,
y=Y1,
showlegend=False,
mode="lines",
fill='toself',
line=dict(color="LightSeaGreen", width=2)
)
polygon2 = go.Scatter(
x=X2,
y=Y2,
showlegend=False,
mode="lines",
fill='toself',
line=dict(color="LightSeaGreen", width=2)
)
fig.add_trace(polygon0, row=1, col=1)
fig.add_trace(polygon1, row=1, col=2)
fig.add_trace(polygon2, row=1, col=3)
fig.update_xaxes(range=[20, 55])
fig.show()
As you can see in the figure polygon 0 and polygon 1 are very different althought are constructed from the same scatter points. The only difference in the arrays is that points 2-(50, 40) and 3-(38, 60) are changed in the array X1 Y1, (2 becomes 3 and 3 becomes 2).
Finally, if you want to close your polygon, you can add an extra point to your arrays equivalent to point 0 (polygon2).
There is a project for plotting Shapely geometries, including polygons, using Plotly
It supports all Shapely geometries, 2D and 3D plotting, and control over colors, lines, markers and fills.
Repeating the example from @Rob Raymond:
import shapely_plotly
import shapely
X0 = [25, 50, 38, 40]
Y0 = [20, 40, 60, 25]
poly0 = shapely.Polygon(shell=zip(X0,Y0))
# Get convex hull
poly1 = poly0.convex_hull
plot_data0 = []
poly0.plotly_draw2d(plot_data0)
shapely_plotly.show2d(plot_data0)
plot_data1 = []
poly1.plotly_draw2d(plot_data1)
shapely_plotly.show2d(plot_data1)
