如何在Plotly Express的px.line_polar雷达图中添加多条线？

方法1：合并数据框，利用Plotly Express的分组功能（推荐） #

Plotly Express的line_polar更适配结构化分组数据，先给两个DataFrame新增分组标识列，合并后直接通过color参数区分组别，自动生成图例：

import plotly.express as px
import pandas as pd

df1 = pd.DataFrame(dict(
    r=[1, 5, 2, 2, 3],
    theta=['processing cost', 'mechanical properties', 'chemical stability',
           'thermal stability', 'device integration']))
df1['group'] = 'Group 1'  # 给df1添加分组标识

df2 = pd.DataFrame(dict(
    r=[.1, .5, .2, .2, .3],
    theta=['processing cost', 'mechanical properties', 'chemical stability',
           'thermal stability', 'device integration']))
df2['group'] = 'Group 2'  # 给df2添加分组标识

# 合并两个数据框
combined_df = pd.concat([df1, df2])

# 绘制雷达图，color参数控制分组，自动生成图例
fig = px.line_polar(combined_df, r='r', theta='theta', color='group', line_close=True)
fig.show()

方法2：通过add_trace手动添加第二条线 #

如果不想合并数据框，可先基于df1生成雷达图，再用add_trace添加df2对应的Scatterpolar对象，通过name参数指定图例名称：

import plotly.express as px
import plotly.graph_objects as go
import pandas as pd

df1 = pd.DataFrame(dict(
    r=[1, 5, 2, 2, 3],
    theta=['processing cost', 'mechanical properties', 'chemical stability',
           'thermal stability', 'device integration']))

df2 = pd.DataFrame(dict(
    r=[.1, .5, .2, .2, .3],
    theta=['processing cost', 'mechanical properties', 'chemical stability',
           'thermal stability', 'device integration']))

# 先绘制df1的雷达图，指定name显示图例
fig = px.line_polar(df1, r='r', theta='theta', line_close=True, name='Group 1')

# 添加df2的雷达线
fig.add_trace(go.Scatterpolar(
    r=df2['r'],
    theta=df2['theta'],
    line_close=True,
    name='Group 2'
))

fig.show()

两种方法都能实现需求：方法1更贴合Plotly Express的设计逻辑，代码简洁易维护；方法2适合需要单独控制单条线样式的场景。

内容的提问来源于stack exchange，提问作者Natasha