如何在 Nodebox OpenGL 中为图的边添加标签？

在 Nodebox OpenGL 中为图的边添加标签时，遇到了问题。使用 add_edge 方法时，遇到了 TypeError: __init__() got an unexpected keyword argument 'label' 的错误。

2、解决方案

为了解决这个问题，可以创建一个自己的 MyEdge 类，该类继承自官方的 Edge 类，并在 draw() 方法中添加一个文本（标签）使用 txt = Text(str, x=0, y=0, width=None, height=None) 或 textpath(string, x=0, y=0, fontname=None, fontsize=None, fontweight=None)。

以下是如何创建一个 MyEdge 类并将其用于为图的边添加标签的示例代码：

from nodebox.graphics import *
from nodebox.graphics.physics import Node, Edge, Graph

class MyEdge(Edge):
    def __init__(self, n1, n2, *args, **kwargs):
        super().__init__(n1, n2, *args, **kwargs)
        self.label = kwargs.get('label', None)

    def draw(self, canvas):
        super().draw(canvas)
        if self.label is not None:
            txt = Text(self.label, x=self.x, y=self.y)
            txt.draw(canvas)

# Create a graph with randomly connected nodes.
# Nodes and edges can be styled with fill, stroke, strokewidth parameters.
# Each node displays its id as a text label, stored as a Text object in Node.text.
# To hide the node label, set the text parameter to None.
g = Graph()

# Random nodes.
for i in range(50):
    g.add_node(id=str(i+1), 
        radius = 5,
        stroke = color(0), 
          text = color(0))

# Random edges.
for i in range(75):
    node1 = choice(g.nodes)
    node2 = choice(g.nodes)
    g.add_edge(node1, node2, 
        length = 1.0, 
        weight = random(), 
        stroke = color(0),
        label = "Placeholder")    #!!!!!!!!!!!!! ADDING THE label HERE

# Two handy tricks to prettify the layout:
# 1) Nodes with a higher weight (i.e. incoming traffic) appear bigger.
for node in g.nodes:
    node.radius = node.radius + node.radius*node.weight

# 2) Nodes with only one connection ("leaf" nodes) have a shorter connection.
for node in g.nodes:
    if len(node.edges) == 1:
        node.edges[0].length *= 0.1

g.prune(depth=0)          # Remove orphaned nodes with no connections.
g.distance         = 10   # Overall spacing between nodes.
g.layout.force     = 0.01 # Strength of the attractive & repulsive force.
g.layout.repulsion = 15   # Repulsion radius.

dragged = None
def draw(canvas):

    canvas.clear()
    background(1)
    translate(250, 250)

    # With directed=True, edges have an arrowhead indicating the direction of the connection.
    # With weighted=True, Node.centrality is indicated by a shadow under high-traffic nodes.
    # With weighted=0.0-1.0, indicates nodes whose centrality > the given threshold.
    # This requires some extra calculations.
    g.draw(weighted=0.5, directed=True)
    g.update(iterations=10)

    # Make it interactive!
    # When the mouse is pressed, remember on which node.
    # Drag this node around when the mouse is moved.
    dx = canvas.mouse.x - 250 # Undo translate().
    dy = canvas.mouse.y - 250
    global dragged
    if canvas.mouse.pressed and not dragged:
        dragged = g.node_at(dx, dy)
    if not canvas.mouse.pressed:
        dragged = None
    if dragged:
        dragged.x = dx
        dragged.y = dy

canvas.size = 500, 500
canvas.run(draw)

通过使用 MyEdge 类，就可以在 Nodebox OpenGL 中为图的边添加标签了。