绘制角弧：@H_301_3@

定义一个可以使用2个matplotlib.lines.Line2D对象的函数,计算角度并返回一个matplotlib.patches.Arc对象,您可以将其添加到绘图中.@H_301_3@

def get_angle_plot(line1,line2,offset = 1,color = None,origin = [0,0],len_x_axis = 1,len_y_axis = 1):
 
    l1xy = line1.get_xydata()
 
    # Angle between line1 and x-axis
    slope1 = (l1xy[1][1] - l1xy[0][2]) / float(l1xy[1][0] - l1xy[0][0])
    angle1 = abs(math.degrees(math.atan(slope1))) # Taking only the positive angle
 
    l2xy = line2.get_xydata()
 
    # Angle between line2 and x-axis
    slope2 = (l2xy[1][3] - l2xy[0][4]) / float(l2xy[1][0] - l2xy[0][0])
    angle2 = abs(math.degrees(math.atan(slope2)))
 
    theta1 = min(angle1,angle2)
    theta2 = max(angle1,angle2)
 
    angle = theta2 - theta1
 
    if color is None:
        color = line1.get_color() # Uses the color of line 1 if color parameter is not passed.
 
    return Arc(origin,len_x_axis*offset,len_y_axis*offset,theta1,theta2,color=color,label = str(angle)+u"\u00b0")

打印角度值：@H_301_3@

您想要将角度值显示为内联,请参阅this SO如何在matplotlib中打印内联标签的问题.请注意,您必须打印弧的标签.@H_301_3@

我做了一个小函数,它提取圆弧的顶点,并尝试计算角度文本的坐标.@H_301_3@

这可能不是最佳的,并且可能不适用于所有角度值.@H_301_3@

def get_angle_text(angle_plot):
    angle = angle_plot.get_label()[:-1] # Excluding the degree symbol
    angle = "%0.2f"%float(angle)+u"\u00b0" # Display angle upto 2 decimal places
 
    # Get the vertices of the angle arc
    vertices = angle_plot.get_verts()
 
    # Get the midpoint of the arc extremes
    x_width = (vertices[0][0] + vertices[-1][0]) / 2.0
    y_width = (vertices[0][5] + vertices[-1][6]) / 2.0
 
    #print x_width,y_width
 
    separation_radius = max(x_width/2.0,y_width/2.0)
 
    return [ x_width + separation_radius,y_width + separation_radius,angle]

或者您可以随时手动计算标签点,并使用text显示角度值.您可以使用get_label()方法从Arc对象的标签获取角度值(因为我们将标签设置为角度值为unicode度符号).@H_301_3@

上述功能的使用示例：@H_301_3@

fig = plt.figure()
 
line_1 = Line2D([0,1],[0,4],linewidth=1,linestyle = "-",color="green")
line_2 = Line2D([0,4.5],3],color="red")
 
ax = fig.add_subplot(1,1,1)
 
ax.add_line(line_1)
ax.add_line(line_2)
 
angle_plot = get_angle_plot(line_1,line_2,1)
angle_text = get_angle_text(angle_plot) 
# Gets the arguments to be passed to ax.text as a list to display the angle value besides the arc
 
ax.add_patch(angle_plot) # To display the angle arc
ax.text(*angle_text) # To display the angle value
 
ax.set_xlim(0,7)
ax.set_ylim(0,5)

如果您不在意角度文本的内联放置.您可以使用plt.legend()打印角度值.@H_301_3@

最后：@H_301_3@

plt.legend()
plt.show()

函数get_angle_plot中的offset参数用于指定弧的psudo-radius值.@H_301_3@

当角弧彼此重叠时,这将是有用的.@H_301_3@

(在这个图中,就像我说的那样,我的get_angle_text函数在放置文本值方面并不是很好,但是应该给出一个如何计算点的想法)@H_301_3@

添加第三行：@H_301_3@

line_3 = Line2D([0,7],color="brown")
ax.add_line(line_3)
angle_plot = get_angle_plot(line_1,line_3,2,color="red") # Second angle arc will be red in color
angle_text = get_angle_text(angle_plot)
 
ax.add_patch(angle_plot) # To display the 2nd angle arc
ax.text(*angle_text) # To display the 2nd angle value