matplotlib / pyplot, lines / 単振り子を描く Polygon(), Circle(), Line2D()

from matplotlib import pyplot as plt
from math import sin, cos, pi

def createPend(length, radian):
    x = length * sin(radian)
    y = length * cos(radian)
    line   = plt.Polygon(((0,0), (x,y)), closed=False, color="black")
    circle = plt.Circle((x,y), 0.1)
    return (line, circle,)
    
    

pend = createPend(1, pi/4)

fig = plt.gcf()
ax  = plt.axes(xlim=(-1.5,1.5), ylim=(1.5,-1.5))
ax.set_aspect("equal")
for obj in pend:
    ax.add_patch(obj)



plt.show()

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線分は matplotlib.lines.Line2D() のほうが簡単であった。

from matplotlib import pyplot as plt
from matplotlib import lines  as mlines
from math import sin, cos, pi

def createPend(length, radian):
    x = length * sin(radian)
    y = length * cos(radian)
    line   = mlines.Line2D((0,x),(0,y))
    circle = plt.Circle((x,y), 0.1)
    return {"line" : line, "circle" : circle}


fig = plt.gcf()
ax  = plt.axes(xlim=(-1.5,1.5), ylim=(1.5,-1.5))
ax.set_aspect("equal")

pend = createPend(1, pi/4)
ax.add_line(pend["line"])
ax.add_patch(pend["circle"])

plt.show()