pyecharts桑基图边颜色设置

pyecharts桑基图（Sankey）的边颜色可以通过`set_edge_color()`方法来设置。该方法接受三个参数：

- source_node：源节点名称
- target_node：目标节点名称
- color：颜色值，支持十六进制和颜色名称

示例代码：

from pyecharts import options as opts
from pyecharts.charts import Sankey

nodes = [
    {"name": "A"},
    {"name": "B"},
    {"name": "C"}
]

links = [
    {"source": "A", "target": "B", "value": 20},
    {"source": "B", "target": "C", "value": 10},
    {"source": "A", "target": "C", "value": 30}
]

sankey = (
    Sankey()
    .add("sankey", nodes, links, linestyle_opt=opts.LineStyleOpts(opacity=0.2, curve=0.5, color="#bbb"))
    .set_global_opts(title_opts=opts.TitleOpts(title="Sankey"))
    .set_series_opts(label_opts=opts.LabelOpts(font_size=12))
)

# 设置边颜色
sankey.set_edge_color("A", "B", "red")
sankey.set_edge_color("B", "C", "blue")
sankey.set_edge_color("A", "C", "green")

sankey.render("sankey.html")

运行以上代码，会生成一个名为`sankey.html`的HTML文件，打开即可看到结果。